I reckon the maxed out beach buggys were great fun to drive and free

One of my favourites was the Lampadati Felon, looks nice and decent speed/handling. Also the one like a Range Rover, both cars are all over the place in the single player yet when you go online they are scarce =/

Also is worth pointing out a AI has to be dumb to some extent to be enjoyable, if the AI was coded to always do the perfect action, it would always win.

This is one reason I dont like human to human gaming as I generally always lose , whilst I enjoy single player games as typically AI can usually be beaten at least eventually.

For me the game is just so dam addictive and thats in my case is the sign of a brilliant game.

And like you said some of the AI are dumbed down deliberately but on the whole i think some of them are really tough cookies .

Certain cars come out at certain times of the day

I like the Coquette, seemed to use that the most