Only at times, unrelated to low or high fuel level in tank, smells inside and outside when it wants to. May go days without smell.

 

If you are a fairly new owner and this has always been there, I would look at the gas pump seal. I had one where the PO had screwed up the installation and made a potential bomb out of it. He wasn't even a muslim, just a bad mechanic.

 

I would look for leaks at the fuel line at the back of the manifold. Should be much stronger smell if you open the hood and sniff around by the ignition coils. If that is it, it is a potential fire hazard if you get a spark plug wire insulation issue that causes a spark to the firewall (common).

 

I had that. Turned out to be a leaky intake manifold ( I think, because it went away after new gaskets). Only sometimes the smell would enter the cabin....

 

Probably leaking at the fuel line, but they had to disconnect it to get the intake off and then reseated it when the gasket was done.