Speed Demon Achievement in Forza Motorsport 4
Reach 240 mph in any car.
How to unlock Speed Demon
Go into an online match, pick the SSC Ultimate Aero and for a track, pick the Old Le Mans track - not the Le Sarth one, as there are kinks in the straight that will not allow you to get up to speed. Doing it in this car is relatively easy, since it puts the Veyron to shame. If you have all of the add-ons, you can also use the Veyron Super Sport... use anything you want, it really doesn't matter to me.