If I smell gasoline on board the vehicle only (not outside the vehicle) while or after the vehicle has been running, but do not see any fluid leaks under the vehicle or in the engine, and have not lost MPG capabilities, then what is causing the smell issue?
You have a gasoline leak. It is a small one since it doesn’t leave a puddle but you have a leak. I’d suggest that leak is in the fuel pump assembly and the gas is leaking onto the top of the fuel tank and then vaporizing so you can smell it.
Get his thing in for service ASAP, before it catches fire.