Original topic: I echo what other people said: "It depends." On your driving style, on where you drive and for how long and whether it's city or highway, and on the availability of cars. I think the cheapest total cost of ownership is an old civic or something.
Oil: My car is a 2000 model. Oil sensor has 1% resolution (I've driven newer cars, eg civics, and they only have 10% resolution - so they tell you your oil life is 100, 90, 80...). I've gotten over 10k miles on it between changes, before the sensor read below 10%. Of course, that required entirely highway miles, which was accomplished by road tripping at 1000+ miles a day on cruise control - the engine moans out its one-note song and there's hardly any call to use oil. Over 100 miles per 1% life. I use either high-mileage synthetic or if it's not available synthetic oil for high-mileage cars (now ain't that a confusing difference); $28 for five quarts of 10W-30. Not only that, but I suspect that the oil sensor is calibrated for conventional oil, so I can likely get a lot more life out of the synthetic stuff, but I'd need to mail a sample to test to know for sure. The sensor is smart; some readouts just do mileage; mine takes into account mileage, rpm, and load. It also helps that my car drives 75-80 at under 2k rpm, only adding maybe 100 rpm for all but the biggest mountains, despite only being a 4-speed. Of course, city driving I get more like 6-7k.
So if my 2000 model can do over 10k miles on a highway or 6k in a city, it would be shocking if new cars couldn't do significantly better than that. It has been fifteen years.
Still, never changing your oil or filter, even in a civic or a camry, is being cheap. I spend $28 on the best oil and another $10 on a performance filter. If you can't afford $38 every five or ten thousand miles, I wonder how you pay for gas. I've heard plenty of "just rolled into the shop" stories of someone not changing their oil for 20k miles and having all sorts of bearings and large metal chunks fall out when the oil got drained. "It runs funny and makes noises." Yeah, you bet it does.