So this achievement requires you to win a race in the game's cover car, the Lamborghini Centenario.
Alright so you can do this one of two ways:
The first (and easiest) way is once you hit 5,000,000 fans, you will unlock a showcase event. This event will require you to win a race in the Lamborghini Centenario against a fighter jet. Simply finish first in the showcase and the achievement is yours.
*EDIT* Thanks to xJohnGalt117x for pointing out that head to head races do not count, you need to win some form of legitimate race.
The second option would be to purchase the Centenario for 2.3 million. While it is a lovely car and when fully upgraded is pretty good, according to AlexStark14 and multiple other users, if you purchase the Centenario and win a race with it, the achievement supposedly doesn't unlock. So I mean just be wary of it if you intend to purchase the car strictly for the achievement, although I don't see the point because this showcase is fairly early on if I remember correctly, but to each his own.
Starting to get the feeling this achievement is simply for winning the showcase event with the Centenario, and the description is just misleading.