Lindsay Lohan -- Another Bad Decision, Vehicularly Speaking

Lindsay Lohan is no Roads Scholar, because she continues to make bad decisions when it comes to cars.

We got this pic of her brand new Porsche -- the entire right side riddled with scratches and dents from an accident.

The good news -- Lindsay wasn't driving. The bad news -- She let the 22-year-old son of a friend drive the whip, which he scraped against a wall while trying to back out of a driveway.

We're told Lindsay is not upset because the kid has insurance and his mom said she'd pay anything insurance didn't cover.

As for the kid -- we're told he "profusely apologized" and Lindsay said she understood.