Will driving or otherwise transferring vehicles between Z-levels (like driving down or up a ramp) be implemented at some point, or are there issues which make programming that impractical? There are a number of possibilities that would make this a worthy feature.
In addition to the traditional mines, you could also have a new map tile: Open Pit Mine. Plenty of large equipment could be found there, easily accessible to the player and any vehicle or mechanical assistance they might need to disassemble the various mining vehicles or machinery. Auger heads or other mining equipment might be repurposed by players to dig tunnel networks or large underground bases. https://en.wikipedia.org/wiki/Open-pit_mining
Being able to dig out an underground garage for your vehicle(s) that you could drive into via ramp would be nice. It would allow you to save surface space for more important things like farmland, and provide a secure area for them that prevents accidental damage, like by a horde pathing through it to get to you.
Parking structures could be added as a new building as well, which would be a place where you might be able to find pristine vehicles or rare vehicle parts, like the enhanced electric motor.
Being able to drive a small vehicle like a motor bike or a 4 wheeler into a sewer via an outlet to a canal or something might be another possibility for moving around unseen. Most aren’t quite this big, but there are ways you could enter a sewer which are human size or larger:
