She's off! Caitlyn Jenner luuuuvs to tool around the grocery store parking lot in Malibu on Sundays to check out hot cars ... and hot ladies!

Cait took her vintage Austin-Healey for a spin and frankly ... it's tiny ... and she's not! Such a cute car, though. But Caitlyn was impressed by some other cars in the lot and on in particular caught her eye. A beautiful blonde had the exact same purple Porsche CJ has and the mystery lady even took Cait for a spin!

The pair spun around the parking lot and Jenner was literally drooling at the sexy car. She and her new friend chatted for quite a while; other celebs were on hand too -- Jay Leno and Pierce Bronson -- but Caitlyn and her car got all the attention.

Cait braided her hair, donned a cap and jumped in her small English convertible and sped home with all eyes on her!