To beat Darius U have to Use a Exotic Car. U could beat Darius very easily, if U unlock the Murcielago in the Canyon race. To win that race use the Lamborghini. Then after winning sell all the cars except the Gallardo . Buy the Murcielago and use it then challenge DARIUS. The first race will be with all three bosses that you have already beaten. This is a sprint canyon, and should be pretty easy if you have infinite nitrous. Never leave the Nitrous button. The next race is also pretty easy. The next race is hard. It is with Darius. The next race is not so hard, it is a Canyon Duel. Just overtake Darius for 10 second and U will win. Then after you beat Darius win the other races, and when all races have ticks you will get a 100% percent in Career.