The movie twins (Skids and Mudflap), and some other cast member alt-modes have been confirmed at a US auto show by General Motors.

http://tformers.com/transformers-che...0962/news.html

Skids - Chevrolet Spark/Beat
Mudflap - Chevrolet Trax
Sideswipe - Stingray Corvette Concept
Jolt - Chevrolet Volt (hybrid plug-in car)