2002 Chevy Impala Smells like gas inside the car

If you have to crank your engine for more than a few seconds during "Cold" start up, then your engine is dumping raw fuel into the exhaust. You will get a strong odor of gas until the engine warms up. (A few minutes)

When you cut the engine off, the fuel pressure regulator may not be retaining enough fuel for the next start up. So you have to crank the motor several times. This will put too much fuel into the cylinders and it won't be burned completely.

Also, you may have an ignition problem that's preventing the fuel from being burned completely. If this is the case, your check engine light should illuminate.

Now, if these systems check out, then you can check for a leaking fuel pump/lines that lead from your tank to your engine. But I doubt that this is the case.