Yeah i got this too....I want the to know when we get the new DLC's im eager to get going on the Drag Mode! Also they need to put in more muscle cars come on SMS/EA do me a favour and put in some Pontiacs!
They need to hurry up with the DLC's and the Drag Mode, ive been waiting for something like this however i have a weird feeling that people are going to spam the life out of the Veyron
Guys from what I see, after level 20 you do not earn much cash, and Shift 2 seems to reward with much less cash than Shift 1, particularly the races done in "Quick" mode out of Career, so me thinks that will be the attraction of the Unlock All Cars DLC because of lack of in-game purchasing power to fill your stable.
FYI: the DLC does not unlock the Bonus/Reward cars though, you still have to earn those the hard way.
After DLC purchase and install the cars are available for $0 price via the car lot, upgrades still cost money and in the event you sell an upgraded car you get the upgrade money back.