The road safety organisation is concerned that drivers unwilling to pay the sky-high prices are neglecting to take a break on long journeys, putting themselves and other drivers at risk.
Its survey of more than 2,000 motorists indicated that 65% now only stop at service stations to use toilet facilities.
IAM chief executive Simon Best told the Daily Telegraph: "Motorway Service Areas are supposed to be for motorists to eat, drink and freshen up.
"It's very important to have a break every two hours and these costs will put people off stopping. Tired motorists pose a danger to themselves and other road users."
The cost of filling up on the go
Motorway service stations take advantage of the fact that customers have nowhere else to go, to ramp up the cost of basic items such as a bottle of water. The IAM research found that a 500ml bottle of water costs up to £2.09 in some serve stations, despite being available for just 95p on even expensive London high streets.
Filling up the car with fuel also costs a lot more on the motorway than it does elsewhere, with motorway prices varying by up to 10p per litre within just a few miles.
How to beat the system
Scottish newspaper the Herald is calling for a review of motorway prices and would like to see petrol stations forced to display their competitor's fuel prices alongside their own - as they do already in France - to allow people to make an informed choice.
In the meantime, however, ways to avoid being caught in the motorway services trap include filling up with petrol or diesel before hitting the motorway and packing a cool box with cold drinks, sandwiches and snacks for the journey.
That is not to say that you should not stop to give yourself a break on long journeys, though.
IAM advises motorists to take a break every two hours, so take advantage of outside space and communal areas to stretch your legs and rest your eyes - even if you don't need to visit the loos.