It will come as no surprise to anyone in the habit of travelling long distances by car that drivers are fed up with the prices charged at motorway service stations.

A sandwich and a drink can leave little change from a £10 note.

Today, car safety charity the Institute of Advanced Motorists (IAM) confirms just how much drivers are paying, with research showing that basic food and drink costs up to four times more in service stations. On average, items bought on the high street cost 25% less than at service stations.

The IAM survey also showed that petrol costs up to 10p a litre more on motorway forecourts compared to urban ones.

This practice is galling to drivers and their passengers who feel they are being deliberately fleeced. Of course it is not obligatory to stop at motorway service stations, but many motorists are loath to divert on spec into nearby towns, simply in search of a cup of restorative coffee, because of the risk of losing time and getting caught in local traffic.

Should it really be too much to ask retailers in service stations to charge more equitable prices? More competition would certainly help: in France, the prices charged by different fuel retailers en route is advertised on motorway-side price comparison boards. The same should be done here: every little helps.

While the high prices are infuriating, however, this is not just a question of money. More important is the question of whether these prices could be putting drivers off breaking their journeys. Driver fatigue is thought to be a contributory factor in a quarter of fatal and serious accidents. For that reason, drivers are advised to take a break every two hours. Motorway service stations are supposed to be convenient places for drivers to stop, stretch their legs, nap if necessary and refuel both themselves and their vehicles.

Yet the IAM fears £3 cups of coffee and £2 bottles of water could be putting some drivers off. Some 17,000 people a year break down on motorways because they run out of fuel. How many do so because they have been trying to avoid filling up at high-cost motorway filling stations? Probably a significant proportion.

An official review of prices would help put the overchargers in the spotlight and force change. It is surely time to put the "service" back into service station.