I've never been able to get all 20 defensive races in one career. You need to start a new career on the same alias (so that everything you've unlocked so far is still unlocked), and win the rest of the 20 in the second go.
To start a new career on the same alias, sell all of your cars except one, then get busted until you get the game over message. You'll then be asked if you want to load your current alias or go to the main menu. Go to the main menu, then start a new career. All of your money and owned cars will be gone, but everything else is as it was before.
-http://freewebs.com/guidetheftauto - my game guide site (GTA, Bully, NFS:C) -http://www.gamespot.com/users/Cyborg_Mantis/games_table?mode=own - My Games
...or just reload the game from your memory card, enter a single race & win you'll be lucky if you get encountered by an attacking crew
That is provided that he left a race incomplete and just repeated completed races over and over again. Then again, I've tried that so many times and I never ever gotten a defensive race.
Anyway, regarding pink slips, if you pick markers that are not the pink slip, don't continue on, but reset your game. That way you can repeat the boss race and take another stab at the pink slip. Mind you, once you restart from the very beginning with the same alias, the bosses won't drop any markers. However, all the cars are unlocked when you restart so it's no big deal (unless you are perfectionist like me and want to have all the boss cars and practically all the reward cards completed within the same files, which is a long and painful process that I really don't want to get into).
AKA bluedragonx - "You either END GAME or don't play the game at all!!"
Sorry, but there IS a method to get the Pink Slip every time. It's been over a year since i've played it and i've lost my notepad that i had notes wrote on. But i do know that it was exactly the same as Most Wanted only with one extra marker. Most Wanted was Cash-Impound/Pink Slip/Jail, and Carbon's is the same method only with Cash and Impound having their own marker now. People can write this off as not working if they want, but i can promise you(to whatever degree you'd like to believe me) that's it worked 100% last time i ran through.
I'm about to Angie though so i'll be trying to figure it out again(I got Kenji's on first try so i didn't try solving it then) so i have it for any future refrences for myself.
I just sold all my cars and lost the last one to restart the game. Once i beat angie, there was no menu to choose cards to get the pink slip. Was that because I've already played? Because before I restarted, the entire career was complete.
I have to say that the markers for the pink slips are in random spots but not order there is a way that you can pick one and afterwords pick the pink slip. for example if you pick the cash and it is on the first stop if i remember correct the pink slip is the 3rd one I forgot which one is to its left and its right but do think that it is always one marker down from the cash