Slow down a bit and take it easy

Infinity Tyres

First and most obviously, the best way to save fuel is to drive with a bit more care, or as if you’ve recently broken your big toe. If your car is revving harder, it’s using more fuel, so don’t be banging off the limiter in every gear, and maybe knock a few mph off that cruising speed.
Equally, a bit of anticipation can work wonders, so be aware when approaching junctions, hills, roundabouts – any slowing down event, really – and cruise rather than abuse. According to some really boring research, cars are typically most efficient at a constant 45-50mph on a completely flat road.

Check tyre pressures and keep your car regularly serviced

A poorly serviced car is an inefficient car, so try to keep up with the servicing, even on an older vehicle. Part of that should be regular checking of tyre pressures – get that wrong and not only do you compromise handling and braking, but you cut fuel efficiency off at the knees.
Tyre companies reckon that between four and 11 per cent of fuel consumption can be down to the rolling resistance of the tyre, and a ten per cent decrease in rolling resistance is equal to a one per cent improvement in fuel economy. So check pressures more than just at MOT time.
Don’t Carry Unnecessary Weight Around
Seems an obvious one, but you’d be surprised how many people keep 50kg+ of nonsense in their cars. And it might not save much, but the less weight you carry, the less work your car has to do, so ditch all the stuff you don’t need.
Don’t Sit Idle Running Your Fuel

Most modern cars have Stop/Start systems these days-where the car will stop the engine while stationary and re-start when you start to pull away – but there are plenty of situations in which sitting with the engine running is literally just burning fuel without motivation. Sure, you need to charge your phone or keep the radio on, but you can do that from the ignition for a bit.

Manage your air-con and cruise-control

Air-con is essentially a big pump that preys on your engine for power, so switching it off helps with efficiency. But that leads to sweaty armpits. So opening the windows at slow speeds is actually more efficient.
Also, cruise control works best on motorways/highways (it stops you accelerating and braking quite so much), so learn how and where to best deploy it.