I have to disagree with you on tires. Before going to Night mode you should change the tires to something else. Having drift tires is like driving on ice.
A couple of my cars are heavy cars with high down force. If I try going up a hill off-road without having enough speed I will get stuck. You can see the tracks in the mud.
Also if I change the down force more grip I find that I can control my car better in a race while cornering. So no I don't think the physics of the game are off.
I will agree that the Cops AI is at a ridiculous level at Night. But maybe that was the point of the developers, to make you think some strategy on how to achieve Rep in order to progress in the game. I had to grid it out to achieve Level 50 as I usually got Busted on Heat 4 & 5.
