Important fact! EVERY home should have a carbon monoxide detector. You can't smell it...and it can kill!
I, too, have a problem with fuel odor coming in the house, but...my furnace is located in the garage! So for the first half hour or so when I get home, the fumes from the car engine get sucked into the furnace and blown in the house. I'm guessing your furnace is NOT in the garage...