how long should a Pontiac G6 last before needing major work done?

Question

engine, transmission, the big expensive things

Answer 1

100,000 miles is not uncommon, but you never know if you'll get the one that loses an engine at 50,000 miles

Answer 2

If you keep good maintenance on the car it could last you for years. But miss a few oil changes. Don`t fix the leaks. Any abusive behavior will shorten the life of any car. Lets just hope that the car will last you a long time. Best of luck with the car.