THE car insurance advice you report suggested that driving fewer miles will reduce the chance of making a claim (“Motorists are hit by serious hike in cost of car insurance”, The Herald, July 23), but reduced mileage is not the whole story. The time spent driving rather than the number of miles driven is a more accurate measurement of accident risk.

For example, drivers A and B leave Glasgow at the same time to drive 300 miles to a location in Yorkshire. With driver A averaging 50mph his journey lasts six hours but driver B averages 60mph so his journey time is 60 minutes less and they are thus exposed to accident risk for one hour less than driver A as they have spent 16.66 per cent less time on the road.

If you are a fuel gauge watcher and think that averaging 60 mph rather than 50mph is a waste of fuel consider this fact: in the final 60 minutes driving time of driver A they will probably use a gallon of fuel and their engine will do about 120,000 revolutions, but during that time driver Bs car will use no fuel and their engine will turn zero revolutions.

The most economical motorway driving speed is the minimum number of revs required for an engine to achieve maximum torque and for many cars this will be around 2,000 and 70mph, so driving slower by choice wastes fuel, exposes the driver to more danger and clogs the roads up.

This also applies to the buying of a used car. Consider the number of revolutions that an engine might have done rather than the miles it’s done, as the smaller the engine the harder it’s worked. A three-year-old 1.2 engine with 30,000 miles might be more worn than a three-year-old 2.0 engine with 50,000 miles on the clock, especially if the latter has been mostly motorway miles.

William McCreath, 14 Finnart Road, Greenock.