The man's 2004 silver Mercedes coupe was parked in the lot of the McDonald's restaurant on Redwood Highway Frontage Road in Mill Valley when the two men pointed a handgun at him and demanded the vehicle around 10 p.m., the sheriff's office said.
The victim turned over his keys and the suspects fled south in the car on Redwood Highway Frontage Road.
One suspect is a light-skinned black or Hispanic man in his early 20s. The second man also was described as in his 20s, the sheriff's office said.
Officers searched the area but did not find the car or the suspects.