Do they have alot of problem with the engines? And how long do they last?
Is this the GTP or GXP model? I can’t advise you on these models. They will have better performance, but use more gas, premium gas.
Most of the Grand Prix have the normally aspirated, reliable 3.8L V-6 engine. They will specify “regular” gasoline. They deliver about 30 MPG hwy. These engines are respected as being fairly “bulletproof”.
As with any used car, have it checked by a reliable mechanic first.
Oh, and another thing, these 3.8s have timing chains, rather than timing belts. That means you shouldn’t have to worry about replacing the timing belt like you would when buying a used car with a belt. I would consider putting on a new accessory (serpentine) belt, though. That takes only a couple of minutes.
How many miles on this Pontiac? Are there any maintenance records that vouch for the car’s care?
How long they last depends on how the car was taken care of before you buy it and after you buy it. With good care, they will live a long time.