Keep your car well maintained
Following the correct service intervals will keep your car running efficiently. New air filters will allow the free flow of air necessary for efficient fuel combustion, clean fuel filters provide a steady stream of petrol to the cylinders, and shiny new spark plugs will provide the spark needed to set the whole thing off. A thing of beauty! They key here is the efficient burn of the fuel air mix, which will allow more power to be extracted from a set volume of fuel. A new air filter alone could reduce your fuel consumption by up to 10%.
Under inflated tyres need more energy to roll. Keeping the pressures at the correct level can increase economy by up to 3.5%. Specialist fuel saving tyres are also available, although these may not perform so well on the track! Properly inflated tyres are also key to providing optimum levels of grip, so it's worth checking periodically.
Using higher gears won't give you lightning acceleration but will save fuel. Keeping your revs low (but not so low that your engine starts to struggle) is a good habit to get into when cruising. If you have a "Sport Mode" on your auto transmission, turn this off, as this will hang onto low gears for longer and may even prevent changing to the highest cog.
Accelerate hard to save fuel?!
A British automotive engineering consultancy claims to have unearthed proof that putting your foot down hard on the accelerator can actually be more fuel efficient than driving more conservatively.
“It sounds totally counter-intuitive — and it is,” admits Cousins. The key to saving fuel, he says, is to accelerate hard until the engine reaches 2000 rpm, move up a gear, then put your foot down until you reach 2000rpm again. It’s all to do with internal friction. “Put simply, with your right foot down on the accelerator, the engine is working at its most efficient,” says Cousins. Above 2000rpm the benefits diminish and you start using more fuel, not less.
Here’s the really interesting thing: in tests carried out in a Citroën C1, one of the most fuel-efficient cars, Cousins’s driving technique proved 8.5% more efficient than the “eco-safe driving” style promoted by the Department for Transport (http://www.dsa.gov.uk — search for eco-safe). The government’s official driving method — taught to all UK learner drivers and now included in the driving test — encourages drivers to save fuel by using the accelerator pedal only lightly.
Dr Steve Cousins should know what he's talking about - he was project leader for the Axon Automotive Caterham 2R which achieved 131 miles per gallon in UK Shell Eco-marathon, and is one of the world's top researchers into fuel economy.
Accelerate gently to save fuel
Although there may be evidence that accelerating hard to 2000rpm could save you fuel, accelerating to the red line in every gear will certainly not. In general, try to keep a constant speed where possible by judging potential reasons to slow down in the road ahead and react to them, avoiding rapid changes in momentum. If you're slowing down and accelerating the whole time, fuel bills will go through the roof.
The faster you go, the harder it is to propel your vehicle through the air. This means that a small decrease in cruising speed could provide fuel economy benefits. The UK's Department of Environment claims that every 5 mph you drive over 65 mph will provide a 7% decrease in fuel economy.