[{"data":1,"prerenderedAt":1191},["ShallowReactive",2],{"blog-depreciation-the-cost-nobody-counts":3,"blog-related-depreciation-the-cost-nobody-counts":165},{"id":4,"title":5,"author":6,"body":7,"category":146,"date":147,"description":148,"draft":149,"extension":150,"image":151,"imageAlt":152,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":154,"navigation":155,"path":156,"readTime":157,"seo":158,"stem":159,"tags":160,"__hash__":164},"blog\u002Fblog\u002Fdepreciation-the-cost-nobody-counts.md","Depreciation: the biggest cost of your car, and the one nobody counts","The Milesheet Team",{"type":8,"value":9,"toc":137},"minimark",[10,14,17,22,25,57,60,64,67,75,78,82,85,88,92,95,98,101,105],[11,12,13],"p",{},"Ask someone what their car costs and they will tell you what they spend on fuel. It is the visible cost, because you hand money over for it in small, memorable amounts.",[11,15,16],{},"For most drivers it is not the biggest one.",[18,19,21],"h2",{"id":20},"the-shape-of-the-real-bill","The shape of the real bill",[11,23,24],{},"Across a typical year, the costs stack up roughly like this:",[26,27,28,36,42,47,52],"ul",{},[29,30,31,35],"li",{},[32,33,34],"strong",{},"Depreciation"," — usually the largest single item on a car under about eight years old",[29,37,38,41],{},[32,39,40],{},"Fuel"," — the one you notice",[29,43,44],{},[32,45,46],{},"Insurance",[29,48,49],{},[32,50,51],{},"Servicing, tyres, MOT and repairs",[29,53,54],{},[32,55,56],{},"Road tax",[11,58,59],{},"A three-year-old car losing £1,200 a year in value, while burning £1,400 of fuel, is not unusual. On a newer or more expensive car, depreciation can dwarf everything else — a £30,000 car shedding 40% in three years is losing about £4,000 a year, roughly £77 a week, while you sleep.",[18,61,63],{"id":62},"why-this-matters-for-a-mileage-claim","Why this matters for a mileage claim",[11,65,66],{},"It explains the 45p.",[11,68,69,70,74],{},"HMRC's approved mileage rate is not a fuel reimbursement. It is meant to cover the ",[71,72,73],"em",{},"whole"," cost of running your own car for business: fuel, insurance, servicing, tyres, road tax and depreciation. That is why it is so much higher than the Advisory Fuel Rates used for company cars, where the company already owns the asset and is absorbing the depreciation itself.",[11,76,77],{},"People who think of 45p as \"generous because petrol is only about 12p a mile\" are comparing it against one line of a five-line bill.",[18,79,81],{"id":80},"the-mileage-connection","The mileage connection",[11,83,84],{},"Depreciation is partly time and partly miles. Two identical cars, one at 6,000 miles a year and one at 20,000, will not be worth the same in three years.",[11,86,87],{},"Which means high-mileage drivers are absorbing a larger cost than the fuel gauge suggests — and it is exactly those drivers for whom recording business mileage properly is worth the most, because the claim is what offsets it.",[18,89,91],{"id":90},"knowing-your-own-number","Knowing your own number",[11,93,94],{},"The honest cost per mile is total annual costs divided by annual miles, not pence per litre.",[11,96,97],{},"Milesheet gets you part of the way automatically: it works out your real fuel cost per mile from your own fill-ups rather than a brochure figure. The rest — insurance, servicing, the value the car quietly lost — is worth adding up once a year, if only to know whether the 45p you are claiming is generous or barely covering it.",[11,99,100],{},"For most people it is generous. For someone running a thirsty vehicle hard, it is not, and that is the case where actual costs deserve a look instead.",[18,102,104],{"id":103},"sources","Sources",[26,106,107,116,123,130],{},[29,108,109],{},[110,111,115],"a",{"href":112,"rel":113},"https:\u002F\u002Fwww.gov.uk\u002Fgovernment\u002Fpublications\u002Frates-and-allowances-travel-mileage-and-fuel-allowances\u002Ftravel-mileage-and-fuel-rates-and-allowances",[114],"nofollow","HMRC — Travel, mileage and fuel rates and allowances",[29,117,118],{},[110,119,122],{"href":120,"rel":121},"https:\u002F\u002Fwww.gov.uk\u002Fguidance\u002Fadvisory-fuel-rates",[114],"HMRC — Advisory fuel rates",[29,124,125],{},[110,126,129],{"href":127,"rel":128},"https:\u002F\u002Fwww.gov.uk\u002Fexpenses-if-youre-self-employed\u002Fvehicles",[114],"HMRC — Expenses if you're self-employed: vehicles",[29,131,132],{},[110,133,136],{"href":134,"rel":135},"https:\u002F\u002Fwww.gov.uk\u002Fvehicle-tax-rate-tables",[114],"DVLA — Vehicle tax rate tables",{"title":138,"searchDepth":139,"depth":139,"links":140},"",2,[141,142,143,144,145],{"id":20,"depth":139,"text":21},{"id":62,"depth":139,"text":63},{"id":80,"depth":139,"text":81},{"id":90,"depth":139,"text":91},{"id":103,"depth":139,"text":104},"Fuel & running costs","2026-01-29","Fuel is the cost you feel because you pay it at a pump. For most drivers it is not the largest one.",false,"md","\u002Fblog\u002Fplaceholder.svg","Placeholder image",null,{},true,"\u002Fblog\u002Fdepreciation-the-cost-nobody-counts",4,{"title":5,"description":148},"blog\u002Fdepreciation-the-cost-nobody-counts",[161,162,163],"running costs","depreciation","buying","c6TUqAWKS_tWB5L3USVioTVXtJLLQI0oX91Cey7RdqI",[166,310,438,566,681,815,951,1044],{"id":167,"title":168,"author":6,"body":169,"category":146,"date":298,"description":299,"draft":149,"extension":150,"image":300,"imageAlt":301,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":155,"meta":302,"navigation":155,"path":303,"readTime":157,"seo":304,"stem":305,"tags":306,"__hash__":309},"blog\u002Fblog\u002Freal-mpg-vs-official-figures.md","Real MPG: why your car never matches the brochure",{"type":8,"value":170,"toc":291},[171,174,178,185,188,192,224,228,231,243,246,251,254,257,261,264,267,270,272],[11,172,173],{},"Almost nobody gets the fuel economy printed in the brochure. That is not because the manufacturer lied, it is because the figure was never a promise about your driving.",[18,175,177],{"id":176},"where-the-number-comes-from","Where the number comes from",[11,179,180,181,184],{},"Official economy figures come from a standardised laboratory test. Since 2017 that has been ",[32,182,183],{},"WLTP",", which replaced the older and much more flattering NEDC cycle. WLTP is a great deal closer to reality than what came before, but it is still a controlled procedure: fixed temperature, a defined speed profile, no headwind, no roof box, no traffic, no you.",[11,186,187],{},"Its job is to let you compare two cars fairly. It was never designed to predict what your commute costs.",[18,189,191],{"id":190},"why-your-number-is-lower","Why your number is lower",[26,193,194,200,206,212,218],{},[29,195,196,199],{},[32,197,198],{},"Short trips."," A cold engine is a thirsty engine. Two miles to the station can return half what the same car does on a motorway run.",[29,201,202,205],{},[32,203,204],{},"Speed."," Air resistance climbs with the square of speed. Seventy costs a lot more than sixty.",[29,207,208,211],{},[32,209,210],{},"Weight and drag."," Roof bars, a boot full of tools, a bike rack you left on since June.",[29,213,214,217],{},[32,215,216],{},"Winter."," Denser air, warm-up cycles, lights and heaters. A 10% seasonal swing is unremarkable.",[29,219,220,223],{},[32,221,222],{},"How you drive."," Anticipation is worth more than any gadget you can buy.",[18,225,227],{"id":226},"working-out-the-number-that-actually-matters","Working out the number that actually matters",[11,229,230],{},"You only need two things: a full tank, and the next full tank.",[232,233,234,237,240],"ol",{},[29,235,236],{},"Fill the tank completely and note the odometer.",[29,238,239],{},"Drive as you normally would.",[29,241,242],{},"Fill it completely again, note the odometer and the litres that went in.",[11,244,245],{},"Then:",[11,247,248],{},[32,249,250],{},"MPG = (miles driven ÷ litres) × 4.546",[11,252,253],{},"That 4.546 is the litres in an imperial gallon, which is what UK mpg is quoted in. Miss it and you will produce a US mpg figure that is 20% too low, which is a classic way to convince yourself something is wrong with the car.",[11,255,256],{},"One tank is a snapshot. Three or four gives you the number to plan with.",[18,258,260],{"id":259},"what-it-is-worth-knowing","What it is worth knowing",[11,262,263],{},"Real economy is what turns a distance into a cost. At 145.9p a litre, a 40-mile round trip costs about £5.80 in a car doing 52 mpg, and about £8.60 in the same journey at 35 mpg. Over a working year that difference is a holiday.",[11,265,266],{},"It also decides whether the 45p a mile you can claim is generous or barely covers the fuel. For an efficient car it comfortably covers running costs. For a thirsty one towing a trailer, it is doing well to break even.",[11,268,269],{},"Milesheet works this out for you: log each fill-up with the litres, the cost and the odometer, and it derives your real MPG between full tanks, then prices every journey with your own number instead of the brochure's.",[18,271,104],{"id":103},[26,273,274,279,286],{},[29,275,276],{},[110,277,115],{"href":112,"rel":278},[114],[29,280,281],{},[110,282,285],{"href":283,"rel":284},"https:\u002F\u002Fwww.gov.uk\u002Fsimplified-expenses-checker",[114],"HMRC — Simplified expenses checker",[29,287,288],{},[110,289,136],{"href":134,"rel":290},[114],{"title":138,"searchDepth":139,"depth":139,"links":292},[293,294,295,296,297],{"id":176,"depth":139,"text":177},{"id":190,"depth":139,"text":191},{"id":226,"depth":139,"text":227},{"id":259,"depth":139,"text":260},{"id":103,"depth":139,"text":104},"2026-07-15","Where official economy figures come from, why the gap is normal, and how two full tanks tell you the only number that matters.","\u002Fshots\u002Ffuel.png","Real-world economy worked out from fill-ups in Milesheet",{},"\u002Fblog\u002Freal-mpg-vs-official-figures",{"title":168,"description":299},"blog\u002Freal-mpg-vs-official-figures",[307,308,161],"fuel","mpg","zHjfx94KQy7kUgWQKR0SVfwXKktsKwGcaHKSRK07ioc",{"id":311,"title":312,"author":6,"body":313,"category":146,"date":427,"description":428,"draft":149,"extension":150,"image":153,"imageAlt":153,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":429,"navigation":155,"path":430,"readTime":431,"seo":432,"stem":433,"tags":434,"__hash__":437},"blog\u002Fblog\u002Fcutting-fuel-costs-same-commute.md","Nine ways to cut fuel costs on the same commute",{"type":8,"value":314,"toc":414},[315,318,322,325,329,332,336,339,343,346,350,353,357,360,364,367,371,374,378,381,385,388,391,393],[11,316,317],{},"You cannot always change the journey. You can change what it costs. Roughly in order of what they return:",[18,319,321],{"id":320},"_1-ease-off-the-throttle","1. Ease off the throttle",[11,323,324],{},"Air resistance rises with the square of speed, so the last ten miles per hour are the expensive ones. Dropping from 75 to 65 on a motorway run typically saves in the region of 10 to 15% of the fuel, and costs you a couple of minutes an hour.",[18,326,328],{"id":327},"_2-anticipate-instead-of-react","2. Anticipate instead of react",[11,330,331],{},"Lifting early for a red light rather than braking late is free. Every drop of fuel you spend building speed you then throw away as heat in the brakes. This is the single biggest difference between two people driving the same route in the same car.",[18,333,335],{"id":334},"_3-check-your-tyre-pressures","3. Check your tyre pressures",[11,337,338],{},"Under-inflated tyres increase rolling resistance measurably, and most cars on the road are down a few PSI. It takes five minutes a month, helps the tyres last longer, and is a safety item anyway.",[18,340,342],{"id":341},"_4-take-the-roof-bars-off","4. Take the roof bars off",[11,344,345],{},"A roof rack or box is a serious aerodynamic penalty at motorway speed, easily 10 to 20% on a small car. If it has been on since the summer holiday, that is expensive storage.",[18,347,349],{"id":348},"_5-empty-the-boot","5. Empty the boot",[11,351,352],{},"Weight matters most in town, where you are accelerating repeatedly. The bag of sand from a job in March is not helping.",[18,354,356],{"id":355},"_6-combine-trips","6. Combine trips",[11,358,359],{},"A cold engine is dramatically less efficient for the first few miles. Three short errands from cold cost far more than one loop that does all three.",[18,361,363],{"id":362},"_7-buy-fuel-on-price-not-on-habit","7. Buy fuel on price, not on habit",[11,365,366],{},"Supermarket forecourts are usually cheaper than motorway services by a wide margin. Filling up before a long run rather than on it is often worth several pounds a tank for a two-minute detour.",[18,368,370],{"id":369},"_8-service-it-when-it-asks","8. Service it when it asks",[11,372,373],{},"A clogged air filter, tired plugs or the wrong oil grade all cost economy. Servicing is not just about avoiding failure.",[18,375,377],{"id":376},"_9-know-your-real-number","9. Know your real number",[11,379,380],{},"You cannot manage what you do not measure. Work out your actual MPG between two full tanks rather than trusting the trip computer, which is often optimistic by a few percent.",[18,382,384],{"id":383},"the-one-that-pays-for-all-the-others","The one that pays for all the others",[11,386,387],{},"If any of your driving is for work, the mileage claim is worth more than every tip above combined. At 45p a mile, 200 business miles a month is £1,080 a year of allowance, and for an efficient car that is comfortably more than the fuel it burned.",[11,389,390],{},"The catch is that unclaimed miles are worth nothing. That is the entire reason Milesheet exists: record the journey while it happens, sort it in seconds, and let the claim add itself up.",[18,392,104],{"id":103},[26,394,395,402,409],{},[29,396,397],{},[110,398,401],{"href":399,"rel":400},"https:\u002F\u002Fwww.gov.uk\u002Fgovernment\u002Fstatistics\u002Fweekly-road-fuel-prices",[114],"DESNZ — Weekly road fuel prices",[29,403,404],{},[110,405,408],{"href":406,"rel":407},"https:\u002F\u002Fwww.gov.uk\u002Fgovernment\u002Fstatistical-data-sets\u002Foil-and-petroleum-products-weekly-statistics",[114],"DESNZ — Oil and petroleum products, weekly statistics",[29,410,411],{},[110,412,115],{"href":112,"rel":413},[114],{"title":138,"searchDepth":139,"depth":139,"links":415},[416,417,418,419,420,421,422,423,424,425,426],{"id":320,"depth":139,"text":321},{"id":327,"depth":139,"text":328},{"id":334,"depth":139,"text":335},{"id":341,"depth":139,"text":342},{"id":348,"depth":139,"text":349},{"id":355,"depth":139,"text":356},{"id":362,"depth":139,"text":363},{"id":369,"depth":139,"text":370},{"id":376,"depth":139,"text":377},{"id":383,"depth":139,"text":384},{"id":103,"depth":139,"text":104},"2026-06-18","No new car, no lifestyle change. The habits and checks that actually move the needle, roughly in order of what they are worth.",{},"\u002Fblog\u002Fcutting-fuel-costs-same-commute",5,{"title":312,"description":428},"blog\u002Fcutting-fuel-costs-same-commute",[307,435,436],"savings","driving","HtlOkwCGZU7tkA18TN1QhrHPgXCVF0htM89hf4v3TjQ",{"id":439,"title":440,"author":6,"body":441,"category":146,"date":556,"description":557,"draft":149,"extension":150,"image":300,"imageAlt":558,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":155,"meta":559,"navigation":155,"path":560,"readTime":157,"seo":561,"stem":562,"tags":563,"__hash__":565},"blog\u002Fblog\u002Fwhy-winter-mpg-drops.md","Why your MPG falls off a cliff every winter",{"type":8,"value":442,"toc":546},[443,446,450,453,456,460,463,466,470,473,477,480,484,487,491,517,520,524,527,529],[11,444,445],{},"If you keep a fill-up log for a year, the shape that emerges is remarkably consistent: economy peaks in summer, sags through autumn and bottoms out in January or February. A 10–20% swing between best and worst month is entirely normal. Here is where it goes.",[18,447,449],{"id":448},"the-engine-spends-longer-cold","The engine spends longer cold",[11,451,452],{},"This is the big one, and it is mostly about short journeys. A cold engine runs a richer mixture until it reaches operating temperature, and oil is thicker so there is more drag to overcome. In summer that warm-up might take four or five minutes. In February it takes considerably longer.",[11,454,455],{},"If your typical drive is twenty minutes, a large fraction of it is now happening at poor efficiency. If your typical drive is two hours, the warm-up barely registers. The same weather hits a short-hop driver far harder than a motorway one.",[18,457,459],{"id":458},"everything-electrical-is-on","Everything electrical is on",[11,461,462],{},"Heated seats, heated rear screen, heated mirrors, blowers, lights, wipers. All of it is load on the alternator, and the alternator is turned by the engine, which burns fuel to do it. Individually trivial, collectively noticeable.",[11,464,465],{},"Air conditioning, incidentally, usually runs in winter too — most cars use the compressor to dry the air when demisting.",[18,467,469],{"id":468},"the-air-is-denser","The air is denser",[11,471,472],{},"Cold air is denser, which means more aerodynamic drag at any given speed. It is a small effect around town and a real one at motorway speeds.",[18,474,476],{"id":475},"tyres-lose-pressure","Tyres lose pressure",[11,478,479],{},"Pressure falls as temperature drops, roughly 1–2 PSI for every 10°C. A tyre set correctly in September can be meaningfully soft by December, and soft tyres cost fuel through rolling resistance. This is the one on the list that is free to fix.",[18,481,483],{"id":482},"winter-fuel-is-slightly-different","Winter fuel is slightly different",[11,485,486],{},"Fuel blends are adjusted seasonally for cold-weather performance, and winter blends carry marginally less energy per litre. It is a small contributor, but it is real and it is not something you control.",[18,488,490],{"id":489},"what-actually-helps","What actually helps",[26,492,493,499,505,511],{},[29,494,495,498],{},[32,496,497],{},"Check pressures monthly through winter",", not annually",[29,500,501,504],{},[32,502,503],{},"Combine short trips"," where you can — one warm engine doing three errands beats three cold starts",[29,506,507,510],{},[32,508,509],{},"Do not idle to warm up",". Modern engines warm faster under gentle load, and idling returns exactly zero miles per gallon",[29,512,513,516],{},[32,514,515],{},"Take the roof box off"," when you are not using it",[11,518,519],{},"What does not help much: driving more slowly than the traffic, or agonising over the heater. Use the heater. You will not save enough to matter and you will be miserable.",[18,521,523],{"id":522},"know-your-own-numbers","Know your own numbers",[11,525,526],{},"The reason to log fill-ups is that this stops being folklore and becomes your car. Milesheet works out MPG between full tanks and charts it, so the winter dip is visible as a shape rather than a suspicion — and if a tank is unusually bad for the time of year, that is worth investigating rather than shrugging at.",[18,528,104],{"id":103},[26,530,531,536,541],{},[29,532,533],{},[110,534,401],{"href":399,"rel":535},[114],[29,537,538],{},[110,539,408],{"href":406,"rel":540},[114],[29,542,543],{},[110,544,115],{"href":112,"rel":545},[114],{"title":138,"searchDepth":139,"depth":139,"links":547},[548,549,550,551,552,553,554,555],{"id":448,"depth":139,"text":449},{"id":458,"depth":139,"text":459},{"id":468,"depth":139,"text":469},{"id":475,"depth":139,"text":476},{"id":482,"depth":139,"text":483},{"id":489,"depth":139,"text":490},{"id":522,"depth":139,"text":523},{"id":103,"depth":139,"text":104},"2026-04-23","Cold engines, denser air, heated everything: the reasons a January tank goes less far than a July one, and how much of it you can do anything about.","Real-world economy and per-tank MPG in Milesheet",{},"\u002Fblog\u002Fwhy-winter-mpg-drops",{"title":440,"description":557},"blog\u002Fwhy-winter-mpg-drops",[307,308,564],"winter","XuWGlLEqaH1GkU1UOiOjXMmqYm3XN90A2Ay1oTjeVkI",{"id":567,"title":568,"author":6,"body":569,"category":146,"date":669,"description":670,"draft":149,"extension":150,"image":671,"imageAlt":672,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":155,"meta":673,"navigation":155,"path":674,"readTime":157,"seo":675,"stem":676,"tags":677,"__hash__":680},"blog\u002Fblog\u002Fsplitting-petrol-with-friends.md","Working out what your passengers actually owe you",{"type":8,"value":570,"toc":662},[571,574,577,581,584,589,592,599,606,610,613,619,625,628,632,635,638,642,645,648,650],[11,572,573],{},"Somebody drives, everyone says they will chip in, and then nobody knows what the number is. It gets settled with a round guess that is either generous or resentful, and often both across the same weekend.",[11,575,576],{},"The number is knowable. Here is how to get it.",[18,578,580],{"id":579},"start-with-what-the-journey-actually-cost","Start with what the journey actually cost",[11,582,583],{},"The honest figure is fuel used, not fuel bought. You want:",[11,585,586],{},[32,587,588],{},"litres used = miles ÷ (mpg ÷ 4.546)",[11,590,591],{},"then multiply by what you paid per litre.",[11,593,594,595,598],{},"A 300-mile round trip in a car doing a real 42 mpg uses about 32.5 litres. At 145p a litre, that is roughly ",[32,596,597],{},"£47",".",[11,600,601,602,605],{},"Note ",[71,603,604],{},"real"," mpg. The brochure figure will understate what the trip cost, usually by 10–20%, and you are the one absorbing the difference. Two full tanks with odometer readings tell you your own number, which is the only one worth using here.",[18,607,609],{"id":608},"then-decide-who-is-paying","Then decide who is paying",[11,611,612],{},"This is where it turns social rather than arithmetic, and there are two defensible answers.",[11,614,615,618],{},[32,616,617],{},"Everyone shares, driver included."," Four people, £47 of fuel, £11.75 each. The logic: everyone is going to the same place and benefits equally, and the driver is already contributing the car, the wear and the driving.",[11,620,621,624],{},[32,622,623],{},"Passengers cover the fuel."," Three passengers split £47, £15.67 each, driver pays nothing. The logic: the driver is providing the vehicle and doing the work, so the least the others can do is cover the consumable.",[11,626,627],{},"Neither is wrong. The mistake is not agreeing which one you are doing until somebody is being asked for money.",[18,629,631],{"id":630},"what-about-wear-and-tear-not-just-fuel","What about wear and tear, not just fuel?",[11,633,634],{},"Fuel is roughly a third to a half of the true cost of running a car once you count tyres, servicing, depreciation and insurance. That is the reasoning behind HMRC's 45p a mile, which is meant to cover the lot.",[11,636,637],{},"For a trip with mates, charging full whack-per-mile usually feels like running a taxi service. Fuel is the convention because it is the cost that visibly happened. Worth knowing the difference, though, before you conclude you broke even.",[18,639,641],{"id":640},"keep-it-out-of-the-group-chat","Keep it out of the group chat",[11,643,644],{},"The thing that makes this awkward is not the money, it is the ambiguity. A figure someone worked out, showing distance and fuel price, ends the conversation. A guess invites negotiation.",[11,646,647],{},"Milesheet costs the journey from your own measured economy, splits it between however many were in the car — with or without the driver taking a share — and shares the drive as a PDF with the route and the numbers on it. Send that instead of a text saying \"about twenty quid?\".",[18,649,104],{"id":103},[26,651,652,657],{},[29,653,654],{},[110,655,401],{"href":399,"rel":656},[114],[29,658,659],{},[110,660,115],{"href":112,"rel":661},[114],{"title":138,"searchDepth":139,"depth":139,"links":663},[664,665,666,667,668],{"id":579,"depth":139,"text":580},{"id":608,"depth":139,"text":609},{"id":630,"depth":139,"text":631},{"id":640,"depth":139,"text":641},{"id":103,"depth":139,"text":104},"2026-04-02","Petrol money without the guesswork: what a journey really cost, how to divide it fairly, and why the driver's share is the argument.","\u002Fshots\u002Ftrips.png","Journeys recorded in Milesheet, business and personal alike",{},"\u002Fblog\u002Fsplitting-petrol-with-friends",{"title":568,"description":670},"blog\u002Fsplitting-petrol-with-friends",[307,678,679],"sharing","road trips","yGk4cxj6qgfNHN7JRDgy4w4S9LCeU1hXpouKNUTqDqg",{"id":682,"title":683,"author":6,"body":684,"category":146,"date":804,"description":805,"draft":149,"extension":150,"image":151,"imageAlt":152,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":806,"navigation":155,"path":807,"readTime":157,"seo":808,"stem":809,"tags":810,"__hash__":814},"blog\u002Fblog\u002Fbusiness-use-car-insurance.md","Does your insurance actually cover driving for work?",{"type":8,"value":685,"toc":797},[686,697,700,704,736,743,747,750,753,757,760,763,767,770,773,775,789,792],[11,687,688,689,692,693,696],{},"Most private policies are written as ",[32,690,691],{},"social, domestic and pleasure",", often with ",[32,694,695],{},"commuting"," added. Neither of those covers driving to a client, a site, or a second office as part of your job.",[11,698,699],{},"If you are claiming mileage for business journeys, it is worth checking that the policy covering those journeys knows about them.",[18,701,703],{"id":702},"the-classes-roughly","The classes, roughly",[26,705,706,712,718,724,730],{},[29,707,708,711],{},[32,709,710],{},"SD&P"," — personal use only. Not commuting, not work.",[29,713,714,717],{},[32,715,716],{},"SD&P + commuting"," — adds travel between home and one permanent place of work.",[29,719,720,723],{},[32,721,722],{},"Class 1 business use"," — adds driving in connection with your work, for you and usually a named spouse.",[29,725,726,729],{},[32,727,728],{},"Class 2"," — as class 1, but with additional named drivers doing the same.",[29,731,732,735],{},[32,733,734],{},"Class 3 \u002F commercial travelling"," — for people whose job is substantially driving: sales rounds, deliveries, mobile trades.",[11,737,738,739,742],{},"The gap that catches people is between commuting and class 1. Driving to ",[71,740,741],{},"your"," office is commuting. Driving from your office to a customer is business use, and it is a different class.",[18,744,746],{"id":745},"why-it-matters-more-than-the-premium","Why it matters more than the premium",[11,748,749],{},"Class 1 usually costs very little to add — often a few pounds a year, sometimes nothing. Driving without it does not usually mean a slightly reduced payout. It can mean the claim is declined and, because using a vehicle without valid insurance is an offence in itself, consequences beyond the accident.",[11,751,752],{},"This is a rare case where the cheap answer and the safe answer are the same answer.",[18,754,756],{"id":755},"the-self-employed-wrinkle","The self-employed wrinkle",[11,758,759],{},"If you are self-employed, the line between \"my car\" and \"the business's car\" is often blurred in practice and completely sharp in an insurer's wording. Carrying tools, stock or goods for sale usually needs commercial cover rather than class 1, whatever the mileage looks like.",[11,761,762],{},"Carrying a passenger for payment — even informally, even a colleague chipping in for petrol — can also fall outside a private policy. Splitting fuel costs between friends on a shared trip is generally fine; charging a fare is not.",[18,764,766],{"id":765},"the-connection-to-your-mileage-log","The connection to your mileage log",[11,768,769],{},"If you are recording business journeys carefully enough to claim them, you already have the evidence of how much business driving you actually do. That is the number your insurer is asking about when they ask how you use the car — and a real figure is a better answer than a shrug.",[11,771,772],{},"It also tends to be smaller than people fear. Many drivers who assume they need commercial cover find that class 1 is the honest description once they see the split between business and personal in front of them.",[18,774,104],{"id":103},[26,776,777,784],{},[29,778,779],{},[110,780,783],{"href":781,"rel":782},"https:\u002F\u002Fwww.gov.uk\u002Ftax-relief-for-employees\u002Fvehicles-you-use-for-work",[114],"HMRC — Claim tax relief for your job expenses: vehicles you use for work",[29,785,786],{},[110,787,129],{"href":127,"rel":788},[114],[790,791],"hr",{},[11,793,794],{},[71,795,796],{},"General information, not insurance or tax advice. Cover classes vary by insurer: check your own certificate and schedule.",{"title":138,"searchDepth":139,"depth":139,"links":798},[799,800,801,802,803],{"id":702,"depth":139,"text":703},{"id":745,"depth":139,"text":746},{"id":755,"depth":139,"text":756},{"id":765,"depth":139,"text":766},{"id":103,"depth":139,"text":104},"2026-02-26","Social, domestic and pleasure plus commuting is not business use. The distinction is small in wording and total in effect.",{},"\u002Fblog\u002Fbusiness-use-car-insurance",{"title":683,"description":805},"blog\u002Fbusiness-use-car-insurance",[811,812,813],"insurance","business travel","self-employed","ASmUjJo8nxe0h-Fb96pVktfrGllQEJikImuWZDCNlXw",{"id":816,"title":817,"author":6,"body":818,"category":146,"date":942,"description":943,"draft":149,"extension":150,"image":151,"imageAlt":152,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":944,"navigation":155,"path":945,"readTime":157,"seo":946,"stem":947,"tags":948,"__hash__":950},"blog\u002Fblog\u002Fwhat-speed-costs-in-fuel.md","What 80 costs you compared with 70",{"type":8,"value":819,"toc":935},[820,823,827,837,840,843,847,850,872,875,878,882,885,911,915,918,921,923],[11,821,822],{},"Most cars are at their most efficient somewhere between 45 and 60 mph. Above that, economy falls away, and it falls away faster the faster you go.",[18,824,826],{"id":825},"why-speed-costs-more-than-it-looks","Why speed costs more than it looks",[11,828,829,830,833,834,598],{},"At motorway speeds, most of the engine's work is pushing air out of the way. Aerodynamic drag rises with the ",[32,831,832],{},"square"," of speed, and the power needed to overcome it rises with the ",[32,835,836],{},"cube",[11,838,839],{},"The practical upshot: going from 60 to 70 costs you something. Going from 70 to 80 costs you noticeably more than that, even though it is the same ten miles an hour.",[11,841,842],{},"Typical real-world figures put the drop at roughly 10–15% from 70 to 80, on top of a similar drop from 60 to 70. A car returning 50 mpg at a steady 60 might see low 40s at 70 and high 30s at 80.",[18,844,846],{"id":845},"what-it-is-worth-on-a-real-trip","What it is worth on a real trip",[11,848,849],{},"Take a 200-mile motorway run in a car doing 45 mpg at 70.",[26,851,852,862],{},[29,853,854,857,858,861],{},[32,855,856],{},"At 70 mph",": about 20 litres. At 145p, roughly ",[32,859,860],{},"£29",". Journey time around 2h 51m.",[29,863,864,867,868,871],{},[32,865,866],{},"At 80 mph",": maybe 40 mpg, so about 22.7 litres — roughly ",[32,869,870],{},"£33",". Journey time around 2h 30m.",[11,873,874],{},"So the faster run costs about £4 more and saves about twenty minutes, before considering that the twenty minutes rarely survives contact with roadworks, and that the faster you were going the more the licence costs if it goes wrong.",[11,876,877],{},"Whether £4 for twenty minutes is a good trade is a personal question. The point is that it is a knowable one.",[18,879,881],{"id":880},"the-things-that-cost-more-than-speed","The things that cost more than speed",[11,883,884],{},"If you actually want to move the needle, these are bigger levers than the last ten miles an hour:",[26,886,887,893,899,905],{},[29,888,889,892],{},[32,890,891],{},"A roof box or bars left on all year."," A box can cost 10–20% at motorway speed. Bars alone are not free either. Take them off.",[29,894,895,898],{},[32,896,897],{},"Under-inflated tyres."," Rolling resistance rises as pressure falls, and pressure falls in winter whether you check it or not.",[29,900,901,904],{},[32,902,903],{},"Carrying weight you do not need."," Less dramatic than the internet claims, but real if the boot is a permanent storeroom.",[29,906,907,910],{},[32,908,909],{},"Stop-start town driving."," No motorway speed is as expensive per mile as accelerating away from lights repeatedly.",[18,912,914],{"id":913},"measure-rather-than-guess","Measure rather than guess",[11,916,917],{},"All of the above is averages, and your car is not an average. The only way to know what any of it is worth to you is to log fill-ups with the odometer and watch what your MPG actually does across tanks.",[11,919,920],{},"Milesheet works out real economy between full tanks and charts it, so a change of habit — or a roof box coming off — shows up as a shape rather than a feeling.",[18,922,104],{"id":103},[26,924,925,930],{},[29,926,927],{},[110,928,401],{"href":399,"rel":929},[114],[29,931,932],{},[110,933,408],{"href":406,"rel":934},[114],{"title":138,"searchDepth":139,"depth":139,"links":936},[937,938,939,940,941],{"id":825,"depth":139,"text":826},{"id":845,"depth":139,"text":846},{"id":880,"depth":139,"text":881},{"id":913,"depth":139,"text":914},{"id":103,"depth":139,"text":104},"2026-02-05","Drag rises with the square of speed, so the last ten miles an hour are the expensive ones. The arithmetic, and what it is worth on a real journey.",{},"\u002Fblog\u002Fwhat-speed-costs-in-fuel",{"title":817,"description":943},"blog\u002Fwhat-speed-costs-in-fuel",[307,308,949],"motorway","z-6pYOLDKVHtslq0f8q2MoQNjpmV3a2qRl-haXk2plM",{"id":4,"title":5,"author":6,"body":952,"category":146,"date":147,"description":148,"draft":149,"extension":150,"image":151,"imageAlt":152,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":1041,"navigation":155,"path":156,"readTime":157,"seo":1042,"stem":159,"tags":1043,"__hash__":164},{"type":8,"value":953,"toc":1034},[954,956,958,960,962,984,986,988,990,994,996,998,1000,1002,1004,1006,1008,1010,1012],[11,955,13],{},[11,957,16],{},[18,959,21],{"id":20},[11,961,24],{},[26,963,964,968,972,976,980],{},[29,965,966,35],{},[32,967,34],{},[29,969,970,41],{},[32,971,40],{},[29,973,974],{},[32,975,46],{},[29,977,978],{},[32,979,51],{},[29,981,982],{},[32,983,56],{},[11,985,59],{},[18,987,63],{"id":62},[11,989,66],{},[11,991,69,992,74],{},[71,993,73],{},[11,995,77],{},[18,997,81],{"id":80},[11,999,84],{},[11,1001,87],{},[18,1003,91],{"id":90},[11,1005,94],{},[11,1007,97],{},[11,1009,100],{},[18,1011,104],{"id":103},[26,1013,1014,1019,1024,1029],{},[29,1015,1016],{},[110,1017,115],{"href":112,"rel":1018},[114],[29,1020,1021],{},[110,1022,122],{"href":120,"rel":1023},[114],[29,1025,1026],{},[110,1027,129],{"href":127,"rel":1028},[114],[29,1030,1031],{},[110,1032,136],{"href":134,"rel":1033},[114],{"title":138,"searchDepth":139,"depth":139,"links":1035},[1036,1037,1038,1039,1040],{"id":20,"depth":139,"text":21},{"id":62,"depth":139,"text":63},{"id":80,"depth":139,"text":81},{"id":90,"depth":139,"text":91},{"id":103,"depth":139,"text":104},{},{"title":5,"description":148},[161,162,163],{"id":1045,"title":1046,"author":6,"body":1047,"category":146,"date":1182,"description":1183,"draft":149,"extension":150,"image":151,"imageAlt":152,"imageCredit":153,"imageCreditUrl":153,"imageIsScreenshot":149,"meta":1184,"navigation":155,"path":1185,"readTime":157,"seo":1186,"stem":1187,"tags":1188,"__hash__":1190},"blog\u002Fblog\u002Froof-boxes-towing-and-drag.md","Roof boxes, bike racks and towing: what they really cost",{"type":8,"value":1048,"toc":1175},[1049,1052,1056,1059,1097,1101,1104,1115,1118,1122,1125,1151,1155,1158,1161,1163],[11,1050,1051],{},"Cars are shaped the way they are for a reason, and most of that reason is air. Anything bolted to the outside interferes with the shape, and the bill arrives at every fill-up.",[18,1053,1055],{"id":1054},"the-rough-ranking","The rough ranking",[11,1057,1058],{},"From most expensive to least, at motorway speeds:",[232,1060,1061,1067,1073,1079,1085,1091],{},[29,1062,1063,1066],{},[32,1064,1065],{},"Towing a caravan"," — economy can halve. There is no trick here: you are pushing a second box through the air and hauling its weight.",[29,1068,1069,1072],{},[32,1070,1071],{},"A loaded roof box"," — commonly 10–20% at 70 mph, more on a small efficient car where the box is large relative to the vehicle.",[29,1074,1075,1078],{},[32,1076,1077],{},"An empty roof box"," — nearly as bad as a full one. The drag is the shape, not the contents.",[29,1080,1081,1084],{},[32,1082,1083],{},"Bare roof bars"," — often 5–10%. Less than a box, absolutely not nothing.",[29,1086,1087,1090],{},[32,1088,1089],{},"A bike rack on the towbar"," — usually gentler than a roof rack, because it sits in air the car has already disturbed.",[29,1092,1093,1096],{},[32,1094,1095],{},"Windows down at speed"," — measurable, though generally less than the air conditioning it is replacing.",[18,1098,1100],{"id":1099},"the-one-that-actually-costs-people-money","The one that actually costs people money",[11,1102,1103],{},"Bars and boxes left on all year.",[11,1105,1106,1107,1110,1111,1114],{},"The trip they were fitted for lasted a fortnight. The 8% they cost carries on until somebody gets a spanner out. Over a year of ordinary driving, that is a real number: on 10,000 miles at 45 mpg and 145p a litre, roughly ",[32,1108,1109],{},"£1,460"," of fuel, so 8% is around ",[32,1112,1113],{},"£117"," for carrying an empty box you are not using.",[11,1116,1117],{},"Ten minutes with a spanner is one of the better hourly rates available.",[18,1119,1121],{"id":1120},"towing-what-actually-helps","Towing: what actually helps",[11,1123,1124],{},"You cannot make a caravan aerodynamic, but you can avoid making it worse.",[26,1126,1127,1133,1139,1145],{},[29,1128,1129,1132],{},[32,1130,1131],{},"Load it nose-heavy within the noseweight limit"," — stability first, but a stable outfit also needs fewer corrections",[29,1134,1135,1138],{},[32,1136,1137],{},"Keep tyre pressures right on both"," vehicle and trailer",[29,1140,1141,1144],{},[32,1142,1143],{},"Slow down."," Drag rises with the square of speed and you are now presenting a great deal more frontal area to it",[29,1146,1147,1150],{},[32,1148,1149],{},"Take the roof box off the car"," if the caravan is carrying the luggage",[18,1152,1154],{"id":1153},"measure-your-own","Measure your own",[11,1156,1157],{},"Every figure above is a typical range. Your car, your box, your speed and your roads will produce your own number, and the only way to find it is to compare tanks.",[11,1159,1160],{},"Log a few fill-ups with the box on and a few with it off, and Milesheet will show the difference as a change in your real MPG between full tanks. It is a satisfying way to settle an argument, and occasionally a surprising one.",[18,1162,104],{"id":103},[26,1164,1165,1170],{},[29,1166,1167],{},[110,1168,401],{"href":399,"rel":1169},[114],[29,1171,1172],{},[110,1173,408],{"href":406,"rel":1174},[114],{"title":138,"searchDepth":139,"depth":139,"links":1176},[1177,1178,1179,1180,1181],{"id":1054,"depth":139,"text":1055},{"id":1099,"depth":139,"text":1100},{"id":1120,"depth":139,"text":1121},{"id":1153,"depth":139,"text":1154},{"id":103,"depth":139,"text":104},"2026-01-15","The bolt-ons that quietly ruin your economy, ranked by how much they cost and how easily you can stop paying for them.",{},"\u002Fblog\u002Froof-boxes-towing-and-drag",{"title":1046,"description":1183},"blog\u002Froof-boxes-towing-and-drag",[307,308,1189],"towing","-RLXZJn1RxAYxReiU1XD-QrusZg5aR5PlJhthhMqbRg",1787331053953]