LeBron James -- Teammate Proves He REALLY Drives a Kia (VIDEO)

LeBron James isn't full of crap in those commercials ...the guy REALLY drives a Kia -- and his teammate, Richard Jefferson, captured the proof on video!

When Bron first started endorsing the brand, NO ONE was buying that a multi-gazillionaire like James would really get behind the wheel of a $50,000 Kia K900 ... instead of a Bentley, Rolls, Ferrari, etc.

But when the Cavs team jet touched down in Cleveland Sunday night -- Bron's Kia was waiting for him on the tarmac (car to jet service?) ... and Jefferson recorded the whole thing.

Jefferson can't seem to believe it and James was laughing during the clip ...

... and all the way to the bank.