The "914 Autobot" (I couldn't think of a cool name for him) is available in shirt & mug form on 914 Reasons.
I think a couple reasons they didn't make this guy in the movies was:
1. May shut down due to vapor lock on hot days
2. Missiles powered by pressurized air in the spare tire.
(There are probably other reasons I'm sure)
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www.914reasons.com