Justin Bieber Struggles to Back Out of Downhill Driveway with Lamborghini

Justin Bieber was revving and roaring his new Lamborghini in town -- but not cruising through streets like you might expect ... he was just trying to get out of a driveway.

Biebs was leaving a church service in Bev Hills Wednesday night, and on his way out ... he seemed to have the hardest time reversing his whip out of a steep entrance/exit.

It's pretty damn funny, especially considering this thing's got something like 730 HP ... and is supposed to be the luxury ride of bull-like caliber. You'd never guess all that, though, by how long it took JB to get up the hill here. And yet ... he eventually got it done.

Side note ... what color do you think this Lambo is? We thought white ... but then had to take a second look.