LAPD Officer: Why the Hell Are You Driving Kim Kardashian's Ferrari??

Kim Kardashian's brand new white Ferrari had its first brush with the law Wednesday night ... TMZ has learned.

An LAPD officer pulled over the expensive whip after noticing it didn't have license plates. But when he got to the driver's side window ... Kim wasn't behind the wheel ... or even in the car.

Instead, we're told the driver was a nice young man with a perfectly good explanation.

Turns out ... Kim had loaned it out to Platinum Motor Sports for a photo shoot earlier in the day -- and an assistant was tasked with the job of returning the car to its famous owner ... when he was popped for the plate problem.