By Shell on Jan. 11, 2022
It’s tempting to think of your car’s fuel economy as a constant. Every car, after all, is bestowed with official fuel-economy numbers to help inform and guide your purchasing decision. But those numbers are merely a snapshot of a laboratory-test moment in time for the purposes of allowing different cars to be compared from a common baseline.
Real-world fuel economy is much more complex and harder to predict; it’s an ever-changing intermeshing of your car’s weight, speed and the aerodynamic drag and rolling resistance it must overcome, along with how it is being driven and even how it’s been maintained.
Confused? Well, don’t be – it just means you have more control over fuel economy than you think. Here’s how to squeeze the most out of each tank.
Lighten the load
A heavier car takes more power to get and keep moving than a lighter one. If you’re driving around with unnecessary items in the boot, your car will be working harder than it has to and using more fuel, so only ever carry what you really need.
Don’t be a drag
Accessories such as roof racks and roof boxes might increase your carrying capacity but they also increase aerodynamic drag. For that reason, they should only be attached when needed, otherwise you’ll just be wasting fuel for no reason.
Keep on top of tyre pressures
Incorrectly inflated tyres can increase your car’s rolling resistance, increasing the power needed to overcome it. To ensure they’re always at their recommended pressures and you’re not needlessly increasing rolling resistance, add a mandatory pressure check to your refuelling regime.
Switch off the a/c at low speeds
Air-conditioning compressors are driven off a car’s engine and can have anywhere up to a 10 per cent impact on economy. Keeping the a/c switched off and dropping the windows instead is the best way to avoid the fuel-economy penalty at lower speeds. At higher speeds, you’re probably better sticking with a/c as the aerodynamic drag of having your windows down can be more detrimental to fuel economy than using the a/c, especially if your car is on the sleek side.
(Learn more about your car’s fuel use and air-conditioning here.)
Let your car do the work
Many cars these days have a drive-mode selector with modes designed to be tailored to different scenarios. If your car has an ‘eco’ mode, use it – while the savings won’t be massive, the brain in your car’s drivetrain will employ early upshifts and other measures to save what fuel it can.
This is the big one – several automotive-industry studies over the years have shown that fuel economy can vary by as much as 30 per cent depending on whether a car is driven smoothly or aggressively. If you’re constantly braking and accelerating too hard, you’ll be wasting fuel. An efficient driver, using the accelerator gently and their forward vision and anticipation to judge and go with the traffic flow, is avoiding unnecessary braking or acceleration and maximising opportunities to coast. They’ll also knock a few Ks off their cruising speeds if it’s safe to do so, reducing aerodynamic drag and allowing the engine to work a little easier.