I turn the car off I smell gas

We need to start with checking the fuel pressure because there is a chance that if this is over pressurizing the system that this is the cause of the smell and using too much fuel.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If the fuel pressure is correct, then I suspect the issue is the purge valve.

This would not account for using too much fuel but is the other likely cause of smelling fuel after the engine is shut off.

I am attaching the info below on the purge solenoid which we should remove and check to make sure it is not stuck open.

https://www.2carpros.com/articles/how-emission-control-systems-work

Please see below for more info and let us know what questions you have.

Thanks