I'm smelling gas fumes outside my car. I can

Fuel tanks have a vent tube and a charcoal cannister to capture the gas fumes from the tank. It's possible there is a cracked or loose hose, faulty fuel cap, bad canister or a fuel leak and any one of many connections. Investigate for sign of raw fuel along the underside of te vehicle, and in the engine compartment. Attempt to follow the smell to isolate the location of a leak.

Have a Dealer take a look at it. Gasoline fumes leaking is flammable as
liquid

gas is a very high evaporative liquid..fumes extremely strong..if overfull it will smell..and if emissions equipment has issues it will smell also.. when the engine gets hot, any gas present will vent off until the engine cools..thats the fuels evaporative nature..still keep an eye out for issues..

Could be two different problems.
If the check engine light is not on, I would look at the vapor canister for the gas tank. Its usually mounted in the engine compartment.
If you have a small oil leak, the fumes will be sucked into the passenger compartment thru the cowl vents.

Hi Doritelberg, If the fuel consumption of your vehicle has increased or there is any sign of a misfire, I believe that one of the injectors may be leaking. For fuel leakages on fuel injected vehicles, it is better to check while the engine is running as the fuel line is pressurized in that state. It would be helpful to know if the smell started after a fuel filter was replaced and what other symptoms, if any you are experiencing with your vehicle? Regards John

Its all connected.
The computer uses a solenoid to vent the fumes from the tank when the engine is running.
The vapor canister holds the fumes until the vent valve is opened.
The computer tried to vent the tank and something went wrong.
It could be from the excessive heat or something with the venting system.
A mechanic would test the venting system.

to much gas fumes can make you ill thats why you fill or transfer gas in a well vented area --will need to look for what vent ,line or component is causing the fumes

On hot days gas fumes will vent from the tank and sometimes you can smell them. If the smell is overpowering there may be resone for concerne and should be checked by a pro. Good luck

It is a fuel pressure regulator. About a $60 item & 20 mintues to change.

I also have a 2004 XC90 and a couple of months ago I had the exact same probelm... after multiple visits to my dealer's auto shop they figured out that it was the fuel pump. They replaced the fule pump and the smell disappeared. Good luck!