I've owned a few cars, 1 was a Toyota Corolla diesel, 1 is a Chevy Duramax and the rest were all gassers. The Toyota diesel was a reliable car, but all of the problems revolved around it being a diesel. It was an '84, so when CA went to low sulfur in mid 90s, the injection pump ate itself, as did many other mechanical injected diesels at the time, according to the mechanic who rebuilt it. A vacuum pump failed ($1200???!!) but I found one at a junkyard for about $120.
The most reliable car was a 1997 Toyota Camry. That car cost $24 in repairs over a 25 yr lifetime - my stepson still has that car and it still drives and rides like a new car. Maintenance cost about $1400 at the 100k mi mark, but this has been by far the most reliable, least expensive car I know of, by a large margin.
I replaced it with a Camry Hybrid that is really nice and looks like it might be as reliable as the other Camry. The best part is it gets 51 mpg city/50 mpg hwy and it's VERY peppy to drive! Most TDI vehicles don't get that kind of economy. Between diesel being more expensive, it always gets on your hands at the pump, diesels being more prone to repairs (they're too complex with too much emissions crap), more expensive to repair, I'm no longer a fan of diesel. The only diesel I would buy would be a heavy duty truck for towing the trailer. I mean a Freightliner Cascadia with 80,000 lb cap.
For a daily driver, I think a hybrid gasser is cheaper and more fuel efficient. I got a brand new 2020 Camry for $23,000 + tax.