A faiure in the EVAP system can cause a fuel smell after you turn the car off, even when the computer has DTC's for it, sometimes it won't show any nor the CEL will be on.
Check the nylon hoses that run from the vent solenoid, located near the windshield at the passenger side, to the intake and the charcoal canister. These can crack or become obstructed. That would also cause low MPG's and the fuel smell of course.