This can be done on any event or online. The Racer event "Fast Lane" from the Porsche Unleashed DLC will get you started on the achievement as you will play through the event while trying to get a Gold Medal. The car isn't that great so if you find yourself doing poorly then just finish the race and do it again and you should have enough shortcut mileage for the achievement.
You can also try it online and have your friend sit at the starting line and let you just drive around in shortcuts until the achievement pops and then finish the event. Then let your friend get the achievement.
Note: this achievement unlocks after you finish the event and leave the Screen that shows how much bounty you wont and your time.