From any series, it's got to have 4 wheels (or a good excuse for more), be generally car shaped and fall under a general definition of deluxe. For me it's a tie between Movie Landmine and Animated Soundwave. Landmine's car mode is just really awesome and he's got nice posability. For Soundwave I really like the shape of his car mode, it's just really boxy and yet also very menacing. It's also hard to beat his really awesome transformation. Oh yeah, and Laserbeak!