I have got that trophy. I am currently at level 25 A-Spec and level 36 B-Spec and have covered over 33,000 miles. When you get further into the game clocking up mileage becomes easy. I ran the Le Mans 24 hour race in B-Spec using the Redbull X1 and the car managed 500 laps which is around 4,300 miles without me even having the TV on.
A quick calculation says that the Le Mans 24 hour race will have to be run 6 times on B-Spec to go from level 35 to 40. Then the Nurburgring 24 hours becomes available and I will do that once. Total mileage to get from level 35 to level 40 and do the Nurburgring race will be approximately 28,000.
I don't think many people will manage that in A-Spec ! LOL