Damaged Box
Dodge Viper Transformer is a dead ringer for the real car but also makes for a very respectable robot
The android form, slyly nicknamed "Side Swipe", using the Viper engine as a big boxy pretend weapon and possessing excellent articulation
When the transformation is complete and Side Swipe becomes a car again, the rubber tires spin quite nicely and combine with solid construction
A robot that transforms into a VW Beetle or a mini-van would just not be all that intimidating