The impact of vehicles are totaly unrealistic.
This lack of reality occurs in many ways, for exemple:
-Specially the helicopters crashing on the ground. They just act act like a heavy BALL, even kick some times.
-When a car crash with a house it simply stops. The walls of the house still undamage and the car looks like new (but dont work anymore). Both acts like rocks, just like a complete solid object not like one made of many parts.
-Some light objects simply totaly stops heavy vehicles at high speeds, without any visual damage and displacement for both of then.
Far from reality or even from older games:
For a best idea: