Raising the motorway speed limit will save fuel

your correspondent Gary Haq (Yorkshire Post, May 24) claims that a reduction of the speed limit (presumably on motorways) will lead to reduced fuel consumption.

In fact it would probably have just the opposite effect, as I will now show with the example of a modern car with six gears, where an engine speed of 1,500rpm produces 20mph in second gear, 30 in third, 40 in fourth, 50 in fifth and 60 in sixth gear.

At 60mph, it will take 10 minutes to cover 10 miles. Reducing the speed to 50mph will take 12 minutes to travel 10 miles, thus running the engine at the same speed in a lower gear for an extra two minutes – thus burning more fuel.

As for the claim that a lowered speed limit would reduce accidents and road deaths, we should consider that motorways are both our fastest roads and our safest roads per vehicle mile.

It should also be noted that many accidents have occurred because the driver of a heavy goods vehicle (governed as it is to 56mph) has nodded off to sleep.

How much worse will the boredom and drowsiness factor become for the driver of a quiet, fast, modern car, forced to travel at an artificially low speed on a wide-open motorway?

Mr Haq’s views do not stand up to examination and the Government would be wise to go ahead and raise the motorway speed limit to 80mph in the interests of driver alertness, the fast transfer of people and goods to the benefit of the economy, and with little or no impact on fuel consumption.