How to Save Money on Gas (Petrol)

Fuel is one of the few bills where your own behaviour moves the number more than the supplier does. The savings are not glamorous, but unlike most money advice they have been measured by government agencies rather than estimated by a blog.

Where does your money actually go at the pump?

Worth knowing, because it tells you which levers exist. The US Energy Information Administration breaks the 2025 average retail price of regular-grade gasoline down like this:

Component	Share of the US pump price, 2025
Crude oil	51.4%
Distribution and marketing	17.8%
Refining costs and profits	16.6%
Federal and state taxes	14.3%

The UK picture is very different, and it is worth seeing the arithmetic. GOV.UK's weekly road fuel statistics for the week commencing 27 July 2026 put average unleaded petrol at 156.13p a litre and diesel at 173.97p, with fuel duty at 52.95p a litre and VAT at 20 percent. Work that through and tax accounts for roughly half the price of a litre of petrol.

That is the honest framing. In the US, roughly half the pump price tracks crude oil, so prices swing with the oil market. In the UK, roughly half is fixed tax, so prices are stickier and the only variable you control is how much fuel you burn.

What actually reduces fuel consumption?

The two national agencies that publish measured figures, the US Department of Energy through fueleconomy.gov and Natural Resources Canada, agree on the ranking. Driving style first, maintenance second, everything else a distant third.

Change	Measured effect	Source
Stop driving aggressively	15% to 30% better at highway speeds, 10% to 40% in stop-and-go	US DOE
Slow down above 50 mph	Each extra 5 mph is like paying 29 cents more per gallon	US DOE
Stop idling	A quarter to half a gallon per hour wasted; 300 ml per 10 minutes on a 3-litre engine	US DOE, NRCan
Inflate tyres correctly	0.6% on average, up to 3%; NRCan measures up to 4% for 8 psi under-inflation	US DOE, NRCan
Use the recommended oil grade	1% to 2%	US DOE
Remove the roof box	6% to 17% on the highway, 10% to 25% at Interstate speeds	US DOE
Take out dead weight	About 1% per 100 lb	US DOE

Read the top two rows again. Nothing else on the list is in the same league. Smoothing out your acceleration and braking and easing off above 50 mph can plausibly change your fuel bill by a fifth, permanently, at no cost.

How should I change how I drive?

Look further ahead. Almost all fuel waste from aggressive driving is acceleration you later cancel with the brakes. Reading the road three or four cars ahead removes most of it without slowing your journey.

Pick a speed and hold it. Cruise control on a motorway or highway maintains a constant speed, which is what fuel economy rewards. On rolling hills, easing off slightly on the climb rather than fighting to hold speed helps more.

Turn it off when stopped. Natural Resources Canada's guidance is to switch off if you will be stationary for more than 60 seconds, other than in moving traffic. Restarting a modern engine uses far less fuel than a minute of idling.

Combine trips. A cold engine is markedly less efficient. Several short separate trips burn more than one longer trip covering the same errands.

What about maintenance and buying?

Check tyre pressures monthly, and more often when the seasons change. It is the cheapest item on the list and the most neglected. Use the placard on the driver's door edge or doorpost rather than the number moulded into the tyre sidewall, which is a maximum rather than a recommendation. Natural Resources Canada notes that under-inflation by 8 psi also cuts tyre life by more than 10,000 km, so the saving is not only fuel.

Use the oil grade the manufacturer specifies, worth 1 to 2 percent. Do not bother buying premium fuel unless your handbook requires it, and do not replace the air filter hoping for fuel economy: fueleconomy.gov is explicit that on modern fuel-injected engines it does not help mileage.

On buying fuel itself, the reliable saving is comparison rather than loyalty. Supermarket forecourts and out-of-town stations are usually cheaper than motorway or Interstate services, and the difference on a full tank normally beats any points scheme. In the UK, the government publishes weekly average prices, which is a useful sanity check on whether your local station is out of line.

The bottom line

Ignore the tricks about filling up on cold mornings. The measured savings are in three places: how hard you accelerate, how fast you cruise above 50 mph, and whether your tyres are at the right pressure. Fix those three and you have taken a real percentage off every tank for as long as you own the car.