Credit goes to SnapDragon for telling me this method. If you don't have 4 actual human players nearby DONT FRET! There is a cool little trick that lets you easily get the achievement. You will still need 4 controllers so get those ready and sign in on each with a different account (can be local, silver, or gold accounts, it doesn't matter). Anyway, once all are signed in, go to local multiplayer and then press A for all controllers. The trick here is everyone needs to pick the Rubber Duck vehicle. For some reason if all 4 humans pick the Rubber Duck, all of the AI players will simply freeze and never move for the entire race! This allows you to get to the finish on all 4 controllers in 1st, 2nd, 3rd, and 4th places. There is no rush either since neither time or AI is against you! After all 4 controllers finish in the first 4 places, you will all get the achievement!
UPDATE: Apparently, a title update has patched this however you can still clear your cache in the dashboard and choose to play the game offline (and this method will still work).