Yaris

To get this achievement you must reach 250 mph on any level and then finish it. There are a few levels to do this on, I suggest level five, but it can be done easily enough on levels three or eight (this can be done on others, but these three levels are generally the easiest).

You will need to find a place where two blue boosters are fairly close to each other. Just hold forward, hit the boosters as you see them and watch where you are driving as hitting anything or getting hit yourself could slow you down. Upgrading your car to the 4-Door S Sedan and wheels to 15 Inch Aluminum will help with this. The shield upgrade may also be useful as well as it will help you stay alive for longer.

Once you reach 250 mph, slow down and concentrate on finishing the level. It will not count if you do not make it out alive. Playing multiplayer with another person may help with this as you cannot die.

For me the 4 door S Sedan Did not work, So i went back to the starter car, i did buy the top wheels although i dont know if they help. Hold up to get your top speed to 150 (my 4door s sedan only toped out at 140)

Head to level eight i think mid track, 2 speed boosters are present hit both and the achievement will pop at the end of the match.
If your having alot of trouble with this achievement, start up a multiplayer match on level eight. Get to the boss and go for it then. You cant die in multi so keep going till you get 250 mph then finish the race