Radar Car: Has farsight and acute senses so that it can detect stealth units.
Radar Tower: Has farsight, acute senses, and scrying.
I don't know if a radar tower would fit, but eh. It might be an interesting way to give the class stealth detection. Cool mod, by the by.

Edit:
This is going to sound extremely petty: Add "Used to make Flame Shotgun Car or Tank" to the description of "Create Flame Shotgun Boxes."
Any plans for boats and aircraft?
Maybe motorcycles? They could be cheaper, yet weaker, than the cars. Give them four move and cars three moves. Then again, that may just be bloat.
Maybe a way to fortify mines?
Is it possible to give repairer vehicles a way to increase healing in the overworld?

Funny Suggestions: A car with a snow plow that has snow move and shoots snow (snow thrower).
Demonically possessed berserker car that exists to run people over.