You must complete 30 laps of the 4x4 Club Circuit R track;
(This track is unlocked by completing the mission 'Road Legal Problems' for the informant at the quarry [northwest on Autobahn map]).
At the Main Menu select Single Race.
Then the easiest way to win this race and unlock the achievement is by selecting the following pre-race options:
Nitro Booster: On
Vehicle Damage: Off
Number of Laps: 30 (as required by achievement)
Number of Opponents: 1
Opponents' Vehicles: Mixed
Oppenents' Strength: Easy
Track Type: Circuits > Autobahn > 4x4 Club-Circuit R
Now complete the race and after all 30 laps, your achievement will unlock.
(You don't even have to win the race, just complete 30 laps).