This will more than likely come through normal game play but if you're impatient like me here's how to get it near the beginning of the game.
To reach Critical Damage usual takes 3-4 crashes (By being taken down or just crashing)
When you first start the game there is a road rage event directly to the left of the beginning Junkyard and there is a repair shop further east of the event.
Hold
+
at the junction next to the Junkyard and once the road rage begins head towards the repair shop, then keep crashing until
'Critical Damage' appears above your car, then as safely as possible drive through the repair shop and the achievement will be yours.
Here's a picture of the first Road Rage location with the repair shop's location.
Here's a video demonstration of the repair in the first Road Rage.