Achievements:
Easy "Eastbound & Down" achievement:
Try using the GT4 Ford Mustang Boss 302R because of its downforce and power.
Note: The Ford Zakspeed Capri does not count as a U.S. car because it was
built by the German Zakspeed team. Choose a single race with no opponents.
You will still get the "Eastbound & Down" achievement if the lap time was
invalidated due to a collision with the track limits.