The man, in his 70s, was saved by brave passers-by who jumped in to rescue him and his dog moments before the vehicle sank.
The video shows the rescuers trying to break the window of the car in a bid to open the driver's door.
As the car begins to sink the female and two males manage to get the back door of the car open and pull out the pensioner before it is swallowed up.
Accountant Alex Kerr who filmed the footage from a nearby cafe was with her family when she heard "this big crunch noise".
"When we looked up we just saw this car floating into the lake, but it had already gone through a metal bollard and chain," said Alex Kerr, who filmed the video from a nearby cafe.
"It just floated off, but it took a while for any of us to realize someone was in there as he was sitting so still inside."
"As soon as that door opened it started to go down quickly but they managed to get him out and all that ended up showing of the car was the open boot," Kerr said.