2004 Buick Century Gas Odor

You could have a leaking fuel line. You should definitely check all the lines that run from your fuel pump in the trunk all the way to your motor. Don't forget that there are lines that send fuel to the engine, as well as a line that sends excess fuel back to the gas tank.

Also, it's possible that your engine is running a little rich during start up, and what you're smelling is just unburned fuel coming out of the tail pipe.

If you must turn your engine over quite a few times on a cold start up before it actually starts, then that's what it is. The smell is just penetrating the cabin.

But fuel vapor is a very dangerous issue. Check everything thoroughly. You could very well pass out inside of your car if you're breathing that in for a lengthy amount of time!