Here is a suggestion. If you are going for the Golden Acts achievements I recommend you play a single race on Outer Forest, but with only one (or two) laps. That because for 1 lap if you win in 1st place the game gives you around 2000 miles, and for 9 laps 7000 miles. So, if you think a bit is better play 9 games for 1 lap = 18000 miles than 1 game for 7000 miles.
So you progress on both achievements
Good luck and sorry for my English :D.