How to Stretch a Tank of Gas

Fuel goes on three things: distance, the way the car is driven over that distance, and time spent with the engine running while going nowhere. Everything below is one of those three levers. None of them is dramatic on its own, and none of them requires spending anything to start.

Take the ones that fit your car and your week and ignore the rest.

Trip stacking

A cold engine uses more than a warm one, which means the first minutes of every separate journey are the expensive minutes. Five short trips from a cold start are not the same as one longer trip with five stops, even when the miles look similar on paper.

So batch. Keep a running note on the fridge or in your phone of everything that needs a drive — the prescription, the parcel, the visit, the shop — and let it build until there is a route through several of them. Then do them in geographic order rather than in the order they occurred to you, and put the furthest point first so you are working your way home.

Errands attached to a journey you were making anyway are close to free. That is where the biggest single change lives, and it costs nothing but a bit of patience while the list fills up.

Driving habits that use fuel without you noticing

Hard acceleration up to a red light and hard braking at it burns fuel to make heat in your brake pads. Reading further ahead and lifting off earlier is the same journey, arriving at the same time, using less.

Speed matters more at the top end than people expect, because air resistance climbs steeply as you go faster. A slightly slower motorway cruise, held steady, costs you a few minutes and not much else.

Idling burns fuel at a standstill. Long waits outside a school or a depot are the obvious case. Warming the car up on the drive for several minutes before setting off is the one people do not think of as idling, and modern engines warm faster while moving.

Air conditioning draws on the engine, and so does driving with the windows down at speed. There is no free option there — pick whichever is bearable and stop worrying about it.

Weight, tires and maintenance

Everything in the boot is being carried everywhere you go. Roof boxes and roof bars are worse than their weight suggests because they push against the air the whole time; take them off when the trip they were for is over.

Underinflated tires make the engine work harder for the same distance. The correct pressure for your car is not a number anybody on the internet should give you — it is on a sticker inside the driver's door frame, in the fuel filler flap, or in the manual, and the figure differs by vehicle and by load. Check it cold, with a gauge, at the pressure that sticker specifies.

Beyond that, the maintenance items that affect consumption are the ones in your service schedule: air filter, spark plugs, oil to the grade the manufacturer specifies. The manual states the intervals for your engine. If money for servicing is not there, at least know which items are the fuel-related ones so that when there is money, it goes on the right thing first.

Route choices that trade distance for idling

The shortest route and the cheapest route are different routes. A shorter way through town with a dozen sets of lights, a school run and a level crossing can cost more than a longer way that keeps moving.

Work out the honest cost of your regular routes by paying attention to how much of each one is spent stationary or crawling. Then test the alternative once, properly, at the hour you actually travel. Traffic apps will show you the timing differences; the stop-start count is the thing to watch, not just the arrival time.

Also worth knowing: hills and heavy loads together are expensive, drive-through queues are idling with a nicer name, and the parking lot space nearest the door is not worth three laps of the parking lot to find.

Deciding which journeys do not happen

Every trip on the list gets three questions. Can this be done without going — a phone call, an online form, someone dropping it off. Can it be attached to a journey that is already happening. Is there a real consequence if it slips to next week.

Anything that fails all three is a journey you can drop without drama. Anything with a hard consequence attached — a shift, a court date, a medical appointment, a child who has to be somewhere — stays on the list regardless, and gets fuel reserved for it before anything else does.

The whole-week version of this, including what to do when the tank will not cover the shifts, is set out in planning a cheap week of getting around.

When driving less is not possible

There is a floor. If the job is a drive away, the childcare is in the other direction and the shifts are fixed, then the miles are not negotiable and no amount of coasting to the lights closes the gap. Pretending otherwise wastes the week.

At that point the fuel stops being a driving problem and becomes a budget question, which means something else in the month has to move. Which thing, and in what order, is worked through in what to cut first from your budget when money is tight.

A few things worth asking about before you assume there is nothing: whether your employer runs a travel loan, a fuel card, a mileage payment or a lift-share board; whether anyone on your rota lives on your route and would split fuel; whether a community transport scheme covers the medical trips specifically. None of that is offered unprompted.

And if the car itself is the problem rather than the fuel — payments behind, repairs you cannot fund — do not let it drift. What happens when a car payment is late explains the sequence, and if the answer turns out to be that the car has to go, earning money without a car is the ground to stand on while you work out what replaces it.