If you win the pinkslips to a Blacklist car, you may want to use the Blacklist car as your own and make the necessary upgrades to performance, as most of the upgrades will have been already made by the Blacklist owner. You do not need to spend too much money to increase the performance, handling, etc. Sometimes these cars will have upgrades that have not been unlocked yet, but most of these are usually visual. Only do this if the vehicle you have won has better attributes than the one you are currently driving in its standard mode. You can check this out in the car shop. Keep about three to five good quick cars in your safehouse.