A large Snickers bar costs 90 pence from a motorway service area compared to 68 pence from a high street branch – 32 per cent more – while a regular coffee costs 16 per cent more on the motorway.  A packet of McCoys crisps was almost 45 per cent more expensive than a shop on the high street, and a packet of Walkers crisps was marked up by 36 per cent.

With petrol prices averaging about ten pence per litre more than at off-motorway forecourts the IAM is calling for a complete review of motorway prices, together with filling stations being forced to advertise their and their competitors’ fuel prices, as is the case in France.

IAM chief executive Simon Best said: “We must end this motorway madness. Everything from sweets to petrol have an outrageous mark up.

“Our advice for tired motorists is always to take your rest break and have a coffee to help you freshen up. The danger is that rip-off prices will discourage people from getting the rest they need. Parking fines for drivers who sleep for longer than two hours put people off taking rest breaks.”