"Reliable" is a generalized term.
I owned a Saturn that I bought at 100,000 miles and drove for 80,000+ miles and it was very reliable and never let me down simply because the previous owner had changed the alternator, ac compressor, bearings, thermostat..... and a long list of parts. So it was a LOT more reliable than a my friend's car which had only 60,000 miles on it, his car went to the shed lot more often.
By "reliable" if you had meant the engine or transmission life, it's hard to say . Engines/transmissions fail anywhere between 10,000 miles and 300,000 miles. It all depends on how well you maintain it and how you drive.
Engines/transmissions don't die one fine day with a cough, they show symptoms well ahead of time.