
Modern cars are designed to completely absorb a hit to spread the deceleration energy all around and thus slow the cabin on a softer manner. These things protect the body of the car but do not spread the deceleration which causes the people inside the cabin to go from moving to stopping nearly instantly. So the body of the car will be nicely protected but the human bodies inside the car will be absolutely wrecked.
Actually part of the reason police budgets are astronomically high in basically every locality is because they have to replace their cars every couple years, because it turns out sitting on the road idling all day only to hard-shift to top gear every time someone speeds by you is in fact not good for a car
That doesn’t seem wise, considering that I’ve seen people brake hard when the realize a cop is behind them, effectively brake checking them. Additionally, drivers are more likely not to obey road protocol in order to be “nice” to a cop car, conversely making the roads more dangerous.