I did this test at a police range in Indiana. We got a car, opened the doors, and shot through them. On this test we used the FN 5.7×28 and the Glock 35 .40 calibers.
The first pictures here are of the 5.7 round. The round was the American Eagle fmj.
In both cases, and multiple angles shot, the rounds deflected slightly upwards. The impact on the second door was higher than were the round struck the first door, even firing at a downward angle. There is approximately a two foot gap between the doors.
These are the results for the .40 cal
This is the .40 cal shot through the trunk and went through the back seat, into the dash. All the .40 rounds used were Gold Dot HP.
This last picture is the windshield. We fired at a target in the drivers seat, and 12 feet in front of the front bumper, all through the back window. All rounds went through the back window and the front windshield. The rear window did not deflect rounds enough to miss the man size target in the drivers seat. The windshield did not deflect the rounds enough to miss the human target 12 feet in front of the bumper.