I have a '99 Metro. I've put a total of 25,000 miles on it so far.
I paid $1000 for it. I estimate its value currently to be $900. Depreciation: $0.005/mile.
I have averaged 44MPG. With gas price fluctuations, that averages out to $0.07/mile.
Registration plus one renewal has cost me $322 (Illinois) total: $0.01/mile
Insurance has been decently cheap (~$50/month): $0.04/mile
Maintenance and repairs have been a bit steep. $1,458.03 total, $0.06/mile. $249 of that was new tires, and $664 was various rusty exhaust fixes. The rest has been pretty normal maintenance.
Brings my total cost of driving to 18.5 cents/mile. If gas stays cheap and nothing else stupid breaks on it for a while, that will go down (the most recent catch-up maintenance and repairs were substantial and little more should be necessary for a while).
I don't think I'll ever drive a cheaper-to-own vehicle until EVs can be bought dirt cheap on the secondary market in 30 years.
Even my big V8-powered station wagon has been pretty cheap to operate:
1992 Buick Roadmaster wagon, over about 30,000 miles
Bought for $700, now worth about $700. Depreciation: $0
Maintenance/repairs ($550 of it being a fuel tank replacement when something on the road blew a three inch hole in my fuel tank, and $90 being a new headlight and window when we hit a fucking deer at 60mph): $966.69, $0.03/mile
Fuel: (18MPG average) $4,593.02, $0.15/mile
Insurance: $668.87, $0.02/mile
Registration, etc: $322, $0.01/mile
Total: 21 cents/mile.