How to unlock all versions of cop cars?

I've been searching and cannot find an answer. Is there a way to unlock all versions of the cop cars? Patrol, Undercover and Enforcer.. going through my career I'm only able to choose one as I go along and I'm not given the option to replay missions to unlock other versions. Will that be available to me later?

Also how do I unlock higher levels of pursuit tech? I'd assume since I'm only rank 6 so far I don't have access to it, but there's no indication of being to upgrade at some later level. So I'm wondering if it's because I'm undercover that I'm restricted to Lvl 1 stuff..

ah nvm, just saw I can unlock the other versions later on a loading screen.

Still don't know about the pursuit tech tho.. maybe i need to start paying more attention to the loading screens..

@PayneKiller: I all you have do is revisit the speedlist on the assignment tree, choose every alternate list than you choose your first run thru to get, the patrol and undercover vers. unlocked, as far pursuit tech I think it goes all the way to 4 or 5 it is not player rank driven its by the car so certain cars only go to level 2 and there done, some go to lvl 3 or lvl4 most of the fastest late unlocks on each side have the most powerful pursuit tech, Once Again there no Tier System in Rivals but if you pay close attention there is, the starter cars, midlist cars, mostly have less goodies than the top 4 or five.