One appliance and crew from Newport Pagnell and one from Bedfordshire attended, along with one officer.
A car was well alight in lane one of the motorway when they arrived. A small area of the verge was also on fire.
The firefighters used one set of breathing apparatus and two hose reels. They dampened down the surrounding area.
Two lanes of the motorway were closed while the firefighters worked at the scene.
Thames Valley Police were also in attendance.