Need for Speed Racing Games

So! I downloaded this sweet little package here with all of the boss' vehicles, and then, the problems begin. As if NFS Undercover isn't loaded with issues to begin with, here is another I cant seem to find solutions for...anywhere, not even Microsoft.

I downloaded the pack, installed, ran great..sweet, I had just restarted my career, so I'm racing against Tier 4 cars with a Tier 1...easy as pie. I go to play online, I pick GMac's Lambo - I'm dissapointed when arriving at the starting line, when I arrive in a Shelby GT500k, up against Lambo's, Veyrons, and CCX's.
I picked my Lotus Elise for the next race, a Tier 4 restricted race, I'm uber-excited at the starting line, because I'm sitting in GMac's Lambo...leaving everyone in my dust. Highly unfair advantage, but it was fun for a few times.
Playing with a few friends - I cant seem to make sense of what cars, are actually going to give me the car I actually wanted, plus..with this I have no Tier restrictions either.

So, there is the dilemma, I understand most people would LOVE to have this glitch going on, but I've tried;
- deleting the boss car pack, re-downloading.
- clearing memory cache
- starting my career over (thinking it was just a saved file corruption)

Annnnd thats the extent of my knowledge on what the hell I can do. Thanks!