Here is a test. Drive your car to an area that is out in the open.
Park the car and proceed to get out. When you're going this (getting out of the car), have a buddy take a couple of shots in your general direction.
See where you go for cover
That being said, most people are quite indoctrinated by TV. When I attended some training recently, one of the other students was addressing a target in a pickup truck. The bad guy lost sight of the student, who ducked and moved all the way around the back of the bed to shoot the bad guy through the open driver's window while the driver was still searching for the student on the passenger side. The instructor said good job, but why didn't you just shoot him through the cab? Two layers of sheet metal and some vinyl isn't cover and you can see where the bad guy is.On TV the car door is cover, in real life it's concealment.