One crew from Gerrards Cross and two crews from the London Fire Brigade, along with two officers, attended a vehicle fire near Denham.
Firefighters found a Porsche well alight on arrival and used one hose reel jet and one set of breathing apparatus to tackle the fire.
Thames Valley Police implemented full road closures while emergency services dealt with the incident.
Crews carried out checks to ensure the scene was safe before the road was reopened.