Travellers should shun motorway service stations and stick to picnics if they want the best food-and-drink deals, it was revealed today.
Prices at service stations are at least twice as high as those at supermarkets, a study by travelsupermarket.com found.
It showed that a family of four could pay nearly £29 for basic sandwiches, crisps, a chocolate bar and a drink at a service station shop, compared with £15 at supermarkets.
A bottle of still water costing as little as 25p at a supermarket averaged as much as £1.27 at a service station.
A sausage roll at a service station would set a traveller back an average of £2.00 compared with just 40p at a supermarket.
Other comparisons include a standard tube of Polo Mints, which are 58p at service stations but only 17p at a supermarket; and a packet of Walkers Crisps, which averages 79p at a motorway stop but only 39p at a supermarket.
The study involved checking prices at 16 UK motorways service stations and comparing them with prices at supermarket Asda.
Bob Atkinson, of http://www.travelsupermarket.com, said: "Following the severe disruptions to air travel this year with snow, volcano eruptions and strikes, many people will be holidaying in the UK this summer or driving to ferry, cruise and rail terminals to avoid flying.
"It might take a bit more time and effort but taking your own food and drink really does pay. It is consistently cheaper to buy snacks, drinks and sandwiches away from the motorway service station at a UK supermarket."