Two numbers, and the second one matters
- Fuel cost is what you will hand over at the pump. It is the number people compare against a train ticket, and it is the wrong one.
- All-in cost adds the share of insurance, tax, servicing, tyres and depreciation that those miles use up. At the UK average of 47p a mile it is usually two to three times the fuel figure.
- Sharing changes everything. Four people in one car is the cheapest long-distance travel in Britain, per head, by some margin.
Claiming mileage?
HMRC’s approved mileage rate for using your own car for work exists precisely because fuel is not the real cost. If you are being reimbursed at a fuel-only rate, you are subsidising your employer.
Sources: 47p per mile all-in — NimbleFins. Fuel maths uses 4.546 litres per imperial gallon. Last reviewed September 2026.