John W is right about context, so let me expand a bit on this in regards to non armored vehicles.
The problem with the idea of using the engine block is that you often don’t get to use it.
The worse case situation is being in a stopped vehicle. Lets say your are static at a stop light or parking lot. Someone is out the kill you in your car. You are not expecting a gun fight If they are within 25 yards, you have little chance even if you are packing a gun in your belt. Your fate is really dictated by the actions of the attacker.
If he closes on you, especially going lateral to get a clean shot on your sides, you are toast. There is just too much shock and awe to the person inside the vehicle, with the glass and stuff flying around. Your reaction time will be greater.
Can you drive away? Sure, maybe if you are on a football field. In real life we often have stuff around us, be it other cars, sidewalks etc. You hit this stuff and it slows you down or stops you dead. With two attackers, the odds are much much worse. All this is why assassinations are easier when the victim is in a car. Most people are lousy drivers in normal situations, let alone getting shot at.
So, the key is distance, not engine blocks and shooting through glass. You create distance by being aware of your situation. You create distance by being a moving target and if you do go static, you do it with situational awareness.
Stopping a moving vehicle is a bit more difficult with gunfire, as most LEO will tell you, IF the person knows you are after him. To stop them, you have to put rounds into the driver, not just the vehicle. You will be lucky to get a clean shot, let alone worry about shooting through glass to hit the driver. Most unsuspecting drivers who take gunfire will rarely recognize what it is, and will often pull over and stop. They probably will not see the shooter, not recognize the report of the weapon, and wonder what hit their car to cause the windshield to explode.
Most range based vehicle training that I have been through was not very realistic for civilians. Maybe for LEOs doing traffic stops, but not for most of us. First of all, you will be lucky to even see your attacker. They will normally be putting rounds into you and your vehicle before you even get to your weapon.
If you are lucky enough to get out of a vehicle, get away from it as soon as it is safe to do so. Cars are bullet magnets because they become the focal point of the attackers. People tend to shoot more rounds and at a higher rate when aiming for big targets.
Well, that is a bit of my view on the subject. Others may have had different experiences.
