Modern gas systems don't allow vapors to leave the tank. This has been true since at least 1990, so evaporation is not an issue.

 

It's been common knowledge that gas vapor recovery systems, required in most states, will not only suck vapors back into the gas station's tank, they will suck overflow gas back as well; better than having it run down the side of your car and all over the gas-pump area. I don't think there's any good way to know when this process starts, so I only fill S-LO-W-L-Y after the 1st kick, and stop pumping if the pump doesn't shut itself off within 1/2 gallon after that.

 

I like to live life on the edge so I usually drive about 40 miles before I fill up. I have been averaging right at about 36 mpg so I should be good for 60+ miles lol