Well, you achieve that once you've completed 20 races. The only ones that Brucie requires you are the 9 races. 3 in Dukes / Broker, 3 in Algonquin, and 3 in Alderney. To do 20 races, simply call him again even after he said that you've done all the 9 races, and simply replay the races.
To find out how many races you've won, go to Stats
and scroll down until you see "Number of races won