2008 grand prix

Inside the car or outside? Inside could be a leaking heater core. Outside would be a cooling system leak of some kind.

Even though you're smelling it inside the car its most likely coming from under the hood. Check the carpet on the passenger side. If its dry its not likely the heater core. If its wet, and if its wet with coolant, then its the heater core. Meanwhile, under the hood... First check clamps and hoses to make sure nothing is leaking. Then check the top of the engine. Intake manifold gasket leaks are common on these cars. The coolant leaks out, runs down over the hot engine and exhaust manifolds and you smell it inside the car. If its a seeping gasket put in some Bars Leak and you should be fine. Also the plastic elbows (also under the hood) that take coolant to the heater core are prone to failing. If they are leaking they need to replaced immediately because any day now they will break and leave you stranded at the side of the road. While you're in there check the water pump too. They often start to leak when they are worn out. If it is its not an emergency, but it does need to be changed soon. It will only get worse.