A dozy driver forgot to put the handbrake on - and is counting the cost after the car rolled into the River Thames and floated towards Craven Cottage.
Stunned onlookers noticed the sinking Volvo S40 by the Embankment near Putney Bridge and watched as it started floating towards Craven Cottage football stadium in Fulham at about 7pm on Thursday.
The police's Marine Support Unit was scrambled from Wapping, while the Met's helicopter was also called to assist with the rescue operation.
As the drama unfolded, witnesses took to social networking site Twitter to express their concern for the driver, but police later confirmed no one was inside the car.
A police spokesman said: "We were called to reports of a car floating in the river after rolling from the Embankment because the handbrake wasn't engaged.
"The tide was coming in and the car started floating towards Hammersmith and by the time it got level with Rotherwood Road it was completely submerged.
"It was dragged out by the time it got to Westminster School Boat Club."
The spokesman urged drivers to take car when parking on the sloping Putney Embankment, which isn't protected by railings.