Only 10 cars in the entire singleplayer campaign are not available from the start and have to be unlocked. Once youve reached a certain Wanted level these cars become available, but you still have to make some effort -
beat the car in a race, then take it down when you see it driving around in the city and then only will it be sitting in its jack spot in the city.
Reminds me of Takedown in NFS Undercover.
SP also adds to your Wanted level, and this time there are 70 levels to grind through. You have to level up in multiplayer to unlock cars for use in multiplayer, unlike the singleplayer game. Once you get to level 70 in Most Wanted you will be reset to 1 again like in many other online games. Criterion are clearly trying to make the online multiplayer a lot more long-lived than Hot Pursuit was.
I don't like the idea of reseting the back to level 1 but at least 70 levels is better than only 20 levels in NFS Hot Pursuit, I reached lvl 20 in less than 2 days just grinding the final race for the cops and racers.
Criterion also confirmed that there is no crash mode in the game. Sadly we will have to wait a little longer for a new Burnout. This game is close but it drives a little less arcadey and has a little more emphasis on cars and modding than a true Burnout game would.
http://www.el33tonline.com/past_article/2012/8/28/need_for_speed_most_wanted/