Depends massively on the car and your willingness to learn about them. My last car before I fled the US was a 2006 camery I inherited that only needed oil changes, tires/rotations, a battery, brakes, plugs, and a timing chain, and got ~28mpg. The timing chain, plugs, brakes, and tires were done by a mechanic friend, so not a whole lot given that I had it for like a decade, total cost was probably about what I sold it for.

My sister on the other hand insists on buying the least maintainable and fuel efficient cars possible on shit credit and I shutter to think what the monthly effective cost of ownership is, probably in the high hundreds.

My current mode of transportation when I'm not in China or Japan is a bike I paid 500 for and gets 100mpg. I put about 60 dollars into a new clutch, chain, sprockets, plug, and foot pegs. It could use a new bore, rings, piston, bearings, transmission, and something is causing a weak spark before its warmed up, and it'll need new tires in a few thousand km, but it's carried me across SEA twice, so none of it's critical, its just the parts are showing signs of abuse.