The move, confirmed in this year’s Budget, is intended to allow drivers to make an informed decision about where to fill up.

Electronic signs will show the real-time price of fuel along the southbound carriageway of the motorway between Bristol and Exeter.

Five motorway service stations along the route are involved in the trial which, depending on the results, could ultimately be rolled out across other parts of the motorway network.

Roads Minister Andrew Jones said: “The Government is on the side of the motorist. We know the public has been concerned about the price of petrol at service stations which is why we have acted to create a fairer deal.

“This trial will allow drivers to be much better informed about the cost of fuel and make it easier to plan their breaks around the cheapest deals.”

The trial will provide fuel information from Gordano, Sedgemoor, Bridgwater, Taunton Deane and Exeter motorway service areas.

It will run until the end of 2017 during which time Highways England monitoring will determine whether increasing the transparency of fuel prices at motorway service areas has an impact on driver behaviour, including the number of stops made at service areas, the number of fatigue and fuel related incidents, and on fuel pricing.

South West Regional Director at Highways England, Andrew Page-Dove added: “We’re working hard to help customers feel safe on the network, to make sure their overall experience on England’s motorways and major A roads is a positive one, and trialling these innovative signs in the South West provides an excellent way of helping us provide an improved service, especially for those millions of people who visit the region each year.

“Our traffic officers dealt with 187,928 breakdowns in 2015, many of which could have been avoided through proper planning and preparation; 2% of these breakdowns were a direct result of running out of fuel. While this appears at face value to be a small proportion, it amounts to 3,672 occasions where drivers could have avoided the risks associated with breaking down.

“This trial is an important part of a bigger picture – we want road users to be more informed and in better control of their journeys. This means they’ll be better prepared, more inclined to plan breaks, have sufficient fuel and have a more positive driving experience.’