Hotshot Racing

Easy! Just do a couple laps of time trial, boosting when possible. Each completed lap fills your boost.

In order to do this easily make sure to go onto a circuit with a good amount of turns and go a car that is high in drift, either max or one off.

Once the race starts and you reach the first corner constantly drift to earn lots of boost and then once on a straight use the boost so you can earn more. use 10 boosts in one race to unlock it.
( If you're struggling to do 10 boosts then go into an arcade race and do more than 3 laps).

While doing this it is also easy to earn the 'catch my drift' achievement.

I got this while playing online in a Cops & Robbers race as a Cop. The boost seems to fill pretty fast while near the Robber racers. I earned this fairly quick (within the first couple laps) without even really trying for it.