You will likely get this achievement at some point without thinking about it (I accidentally got it on my second race). As Illisia mentioned, the start-of-race bonus in Stunt Runs WILL count as hitting something, as will breaking through any billboards in later levels, so avoid doing that if you're going for this in a Stunt Run mission. Other than that, just don't crash or bump into the environment or other vehicles, and you'll have it in no time. The first Stunt Run mission of the game is a good place to get this, due to the lack of vehicles, only jumps.