You used a flashback to take you to victory after facing defeat.

Just keep all your settings as you like them, but make sure to change the damage to full. Now either run into a tree at a fast speed or drive off a cliff. The announcer will explain how a flashback can save you (but costs you driver rep), and you will be put into a replay. Hold "LT" to rewind, and press "X" to restart your car at the position you selected. Now just complete the race, making sure to win, and the achievement will unlock shortly after the event is over.

hoped i helped
-Toes