The black car, estimated to be worth around £100,000, somehow ended up off dry land and floating in the water.
The St Agnes Coastguard Search & Rescue Team were called to Trevaunance Beach, in St Agnes, at 8.30am on Sunday.
The local team checked that the occupants were out of the vehicle and safe and then started the recovery process.
Footage and pictures posted by the coastguard rescuers on its Facebook page show the BMW partially submerged in the water.
The vehicle was then rescued from the sea and part of the car can be seen pouring with water from the back door area and exhaust.
The BMW is then pictured being loaded onto a truck and was presumably towed to a garage.
It is not clear how the car became submerged in the water. No injuries were reported.
In a post on Facebook, the rescue team said: “Team tasked to the Trevaunance Beach car wash to make sure all occupants were out of the vehicle and safe.
“We remained on scene whilst recovery efforts were made and the vehicle was finally removed.
“Team stood down and returned to station at 1019hrs. ‘You can’t park there sir!’”
Social media users were hardly sympathetic to the plight of the BMW owner, who was branded a “disgrace” and criticised for “wasting resources”.
However some others saw the lighter side, one person said: “The lengths some people will go to to avoid the £3 car park fee!”
And another said: “Did someone forget to tell the tide that BMWs can park anywhere they want.”