Police and firefighters from Bracknell police station were called to North Lake, opposite the Birch Hill mansion, at around 3am to find a silver Renault partially submerged in the water.
Officers believe the vehicle was stolen.
The fire crew spent 45 minutes at the scene and had to wait for a special boat crew to arrive from Caversham before retrieving the vehicle - which was about five feet into the lake.
The car was unoccupied and no-one is thought to have been injured.
Police were hoping to recover the car from the bank of the lake this morning.