Star in a Reasonably Priced Car achievement in Forza Motorsport 4

You can either enter "Rivals" from either the "Community" or "Career" tab, then select "TopGear Rivals", or select "Free Play",and either "Quick Race" or "Hot Lap", then select Kia Cee'd as a car, and select Top Gear, then Full Circuit. The achievement will pop after your first lap.

Thanks to piwo4me for additional info!