“I am quite sure engineers could easily build and market a comfortable car that would last 400,000 miles and cost under $10,000.”
For city driving UTV’s should be legal, they will get 35+ MPG and are less than 10K.
Check out Mahindra Roxor, not under $10K but something like you are talking about.
Many if not most states allow cities to adjust local ordinances for licensing UTVs for street use...
Kits to make your UTV street legal can be found online in the 200$ price range...
Just the thing for pizza and beer runs...