How do you get prototype races unlock?

All you have to do is to enter A pink slip race and try to gamble with you car, when you are about to bet, choose the player you wanna race with, look at the botton corner of the colomn with the car information, there is a car information eg L2 77 SOMETIMES IN BLACK OR GOLD, THAT L2 indicate the highest level that the car could reach in the game, If the colomn is painted in black the car is not prototype model but if the colomn is gold it means is a prototype and thats the car you need.enter the race, win the car, after winning go to the garage modify the car, bear in mind whenever you are modifying be careful not to downgrade the handling as that would change the prototype to ordinary car.what I did was, I bet a pink slip with crystal her car was GT are-34 SKYLINE at stage 5 and this car could play or compete at different stages of the game, after winning the pink slip I upgraded the car till it is promoted to play in stage 2, where the promotion event requires a prototype car.try that. Try that and beat the game. Remember only the pink slip can only help you get a prototype car.goodluck

Guys, this is Themvuk again as I previously replied to this question and still some don't get it right, so pls listen carefully, if you have already reach league 2 ( ZEX) and youre struggling to play the promotion event because you don't have a prototype car, to enter the race, this is what you have to do.go back and play pink slips from league 6 and 5. Play all pink slip especially the circuit race as here you can not easilly loose your car to whoever you might challange against. Win some of this pink slip . Remember all the cars you can win at these leagues ( 6 and 5) they can be upgraded but they will never play in league 2 even though some of them would be prototype, nevertheless upgrade them to whatever level they can reach or play.now that you have played all the pink slip of league 6 and 5 now go to league 4 ( NITROUS EXPRESS), pay attention because the car you need is here, go to the columns you have to complete in this league,the first colomn is the promotion event , you skip that one as it is still locked, the 2nd colomn is win the circuit race, enter that one,scroll till you get the pink slip, you can leave or play it , next to it is another pink slip called FULL IMPACT, enter that one, you can used any prototype car that you won and upgraded to this league from league 6 and 5, challenge crystal, her car is skyline R34 GTR, win the race and take the car , this is the only car that can play at league 2 still with prototype, now listen again, after winning take the car to the garage for modification, install power, weight and extreme nitro under league 2 modification not 3 because youre already at league2 but never install anything under handling as this could change the car from being prototype. From there the car will be promoted to play in league 2 and thats where you are stucked. Pls again don't install anything under handling. For those who are still under league 5 when you reach league 4, win that car and upgrade it to the next league whenever youre promoted till you reach league 2and that means whenever you upgrade the car you will be installing everything except the handling.goodluck guys