This achievement is a lot easier than it seems. It is best to do it on easy or medium rather than hard. Select a "Time Attack Race" (These are in the Tuner series, 3rd row.), then try to set a 1st place time on the first or second lap. You need to have a first place time by about 4 seconds. Then on your 3rd and final lap about 100 meters or so before the finish line, flip around and cross backwards.