One appliance and crew from Beaconsfield and one from Hillingdon attended.
One car was well alight on the hard shoulder of the motorway when they arrived.
The incident generated multiple calls to Thames Valley Fire Control Service.
The firefighters used one set of breathing apparatus and one hose reel jet.
Lanes one and two of the motorway were closed while they worked at the scene.
The car was destroyed by the fire.
National Highways also attended.