I have a 2016 XC90 (purchased March 2016). Approx 10K miles so far. The car stays parked in the garage by itself. We have been noticing a very prominent gasoline odor in our garage. The odor is more prominent when the weather is colder and we notice is predominantly after the car has been parked in the garage for a while (i.e don't notice much when we getting back home and unloading the car)

We took it to the dealer a couple of months ago and they said they didn't find any leaks. However, the problem seems to be getting worse (we are noticing the smell more often and it is getting stronger). So, we intend to take it back but before we do, wanted to get some advice here on -

1) Has anyone faced such an issue (or anything similar)?
2) Any tests/self-diagnosis I can do myself before heading to the dealer? (to help them point in the right direction since this is a hard problem to recreate at the shop)
3) Any tips on what to alert the dealer to? (maybe they are not thinking hard enough)...

Thanks for helping.