Gas Spill on Carpet (no specific Audi content)

[Steve Sherman <Steve.Sherman@nsc.com>]

My wife was filling a gas can a couple days ago and did not tighten the
cap sufficiently. So a bit of gas leaked from the can onto the passenger
side carpet (I know, I know, but there was a good reason that the can
was on the floor in the passenger area instead on in back). I would
guess 1/2 liter or more of gas may have run out onto the carpet.  

The question of course is how to get the gas odor out.  I've tried
vacuuming with a shop vacuum, carpet shampoo and washing with water, and
leaving a small elec. heater with fan on the area.   All help, actually
quite a bit the odor is virtally gone as long as the windows are open,
but very noticible with the windows shut now.   

I would like to speed up the eventual evaporation.  Any BTDT's out
there?  Any soaps or detergents that might really make a difference on
the gas?

TIA

Steve