London, June 11 : Driving more slowly will save drivers up to 500 pounds a year in fuel costs, according to a study, which reveals that the most efficient speed is much lower than most people think.

Car manufacturers suggest that the optimum speed for fuel efficiency is between 50mph and 60mph and a recent survey found that two thirds of drivers believe this to be the case, The Times reported.

But the study, commissioned by What Car? magazine and based on five cars of different sizes ranging from a one litre Toyota Aygo to a 2.2 litre Land Rover Freelander, found that the most efficient speed was below 40mph for all five and as low as 20mph for two.

The study comes as the British Government prepares to put in place emergency measures to prevent a strike by Shell oil tanker drivers from creating fuel shortages across the country.

The Downing Street urged drivers on Tuesday not to panic buy, which would cause shortages even if fuel deliveries continued as normal.

The study, by Peter De Nayer, a former AA fuel efficiency expert, involved fitting cars with a fuel flow meter and testing them in Bedfordshire. He found that a Citroën C4 1.6 diesel achieved 99.6mpg at 20mph but only 29.3mpg at 90mph.

The average car consumes 38 per cent more fuel at 70mph than it does over the same distance at 50mph. At 60mph it uses 34 per cent more than at 40mph.

The average driver travelling at 90mph on a motorway will spend 1.20 pounds more on fuel every eight minutes than a driver travelling at 70mph. The 90mph driver will have travelled farther in that time but will still be spending 40 per cent more per mile than the 70mph driver.

The study also found that a driver of the average car travelling 10,000 motorway miles in a year at 80mph would spend 518 pounds more on fuel than if he had driven the same distance at 60mph.

“There is a huge misconception that the most fuel-efficient speed is around 55mph. The study shows that the slower you go with the vehicle running smoothly, the less fuel you will use,” De Nayer said. (ANI)