In the "Valley Fever" rhythm track while still in the "searching for players" part of the race, turn left and drive behind the crowd until you see a long Asphalt stretch with trucks. While stationary, hold down clutch (
) , throttle (
), and down on both sticks. Released clutch and balance for the proper distance. Took me about 5 or 6 tries but it's very doable when you get a feel for it. I crashed after doing my distance and the achievement still popped right away.