This was something I noticed fairly recently. None of the police cars have any sort of barrier between the driver and "criminal" part of the car. There's nothing separating criminals from the officers, which doesn't seem right. I don't know about you, but I've never seen a police car without one of these dividers. I know I'm not doing a great job of explaining things, so I'll let the pictures explain: Police Grand Marshal: Real police car: This seems like it shouldn't be too hard to implement, but would add to the game.