One appliance and crew from Broughton, one from West Ashland and one from Newport Pagnell attended, along with an officer.
The car was on its side, in a ditch.
Two men, injured, and one woman, injured, were cared for by South Central Ambulance Service.
The firefighters used a short extension ladder and stabilisation equipment.
The motorway was closed while they worked at the scene.
National Highways and Thames Valley Police were also in attendance.