MOTORWAY drivers who habitually cruise at 85 mph not only break the law and risk lives, they also burn up a quarter more fuel than if they had stuck to the national speed limit, according to AA petrol consumption tests.

For every 10 miles that a 1.8-litre higher performance saloon car travels at well over the speed limit, it increases its fuel bill by 21 pence. A 1.3-litre car squanders almost as much, 20p over 10 miles.

Heavy braking for slower traffic and then steadily accelerating back over the speed limit adds to the drain on fuel, costing drivers and UK companies hundreds of pounds.

"Not only is there a safe argument against driving well over 70 mph, there is an environmental and financial price to be paid," says the AA's Chief Engineer, David Lang. "Over 10 miles, a car breaking the motorway speed limit by 15 mph or more uses up an extra third of a litre on fuel. This pumps an additional 0.8kg of CO2 into the atmosphere, enough to fill the car's boot if it was piped back inside.

"These figures will make many car fleet managers realise that hefty fuel costs may in part be caused by their employees driving behaviour. As for the private motorist, sticking to the speed limit over a long trip could save perhaps a quarter of a tank of petrol or pay for a relaxing meal at the end of a journey."

British motorists now pay four times more for petrol than US drivers, 80 per cent of which goes as tax to the UK Treasury. The AA believes that drivers can reduce this high cost if they know how.

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