Official fuel economy figures have come under increased scrutiny over recent years as people struggle to replicate the figures on the road.
To help your petrol or diesel go a little bit further here we explain what affects fuel efficiency, why you can’t hit those impressive official figures and what small changes you can make today to improve your overall economy.
Official figures versus real-world driving
All cars are currently tested in a 45-year-old programme called the NEDC (New European Driving Cycle), which was last updated in 1997. It takes place in laboratory conditions, where cars are tested on a rolling road using a pre-determined test pattern for approximately 20 minutes. The artificial route includes city and motorway driving, plus periods of idling, acceleration and braking, all conducted in controlled temperatures and conditions.
Although in theory that sounds quite representative of the driving we do day-to-day, the test doesn’t take into account changing climatic conditions such as wind and rain, varying terrain like steep hills plus there are no traffic lights on the test. None of the test cars are filled with passengers or luggage and fuel-sapping equipment like air-con and heated seats are turned off, too.
Research suggests that the gap between your ‘mpg’ and the official figures can be as high as 40 percent – especially if you’ve bought a larger car with a downsized engine.
It’s very likely that the outdated test will change in the near future to be more representative, especially in light of the recent Volkswagen emissions scandal. For now it provides a benchmark to compare cars against each other.
There are also a number of things we can do as drivers to improve our fuel efficiency:
Driving style
Speed is probably the most obvious factor when it comes to improving your fuel economy; the faster you go, the more fuel you’ll use.
Accelerating quickly or braking hard uses more fuel – adopting a smoother driving style is proven to improve fuel efficiency, including changing gears as and when the dashboard indicator suggests it for optimum economy.
You don’t need to have everything but the kitchen sink in the boot for your commute to work. Clutter in your car adds weight, requiring more fuel to make it move.
Most of us cannot avoid the daily traffic jam at rush hour on our commutes but trying alternative routes and checking traffic alerts before you leave for longer journeys could save you time and money.
Constantly stopping and moving off again uses more fuel so read the road further ahead and slowly approach traffic lights or queues of traffic – you might avoid having to stop at all.
Equipment and air-con
Modern cars come with a whole host of advanced kit, from systems which can park the car for you, heat the steering wheel, steer you back into lane or give you a birds-eye view when reversing.
All these systems need power to work though and use fuel in the process, especially air-con and heating systems, so if you don’t need them, turning them off will save fuel. Just be aware that air-con works in colder months too, helping demist the car’s windows more quickly.
Lots of cars today are also fitted with fuel-saving technology like stop/start which will automatically shut the engine off when you stop in traffic. Low-rolling resistance tyres are also a popular choice for better fuel economy.
Regular maintenance and tyre checks
To maximise fuel efficiency your car needs to stay in tip-top shape and keeping fluids topped up and tyres correctly inflated will help make your next gallon of fuel stretch further.
Regular maintenance checks are important for a number of reasons: they could help to avoid costly trips to the garage and when your car runs at its optimum it should perform more effectively when it comes to fuel economy. You’re also keeping your insurance valid by keeping the car regularly maintained.
The key fluids to check under the bonnet are the engine oil, screenwash and coolant. All three should stay topped up and we would recommend checking these every couple of weeks or before a particularly long journey. Although many new cars will alert you if anything needs changing, it’s always good to check.
Incorrectly inflated tyres wear out quicker, unbalance the car and use more fuel. Check your tyres every month to make sure the pressures match those in the manual and that they don’t have any cracks, cuts or excessive wear on them. Also ensure the tread depth is not below the legal limit of 1.6mm.
Top tips to help the environment
- Use official figures to compare cars against each other to find the most economical choice – remember CO2 emissions and fuel economy are directly linked, more economical cars generally emit less CO2.
- Regular maintenance checks will help keep your car running at its best so the engine will not have to work harder, using less fuel in the process.
- Driving style is one of the most important factors to consider when you want to improve fuel and CO2 – avoid quick acceleration and harsh braking when possible.
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