The past 5 days I've been dealing with my wife finding a couple of teaspoons of sugar all around and inside the fuel filler when she gassed up. I had heard as a kid in the 50's that sugar in gas would ruin an engine and was puzzled my wife had driven at least 50 miles with no symptoms. When I talked to my mechanic about steps to take such as towing the vehicle in, etc, I was surprised he and another mechanic recommended doing nothing unless I had symptoms of fuel line blockage as they thought the sugar would not dissolve in gas and would be kept in the tank by the fuel pump intake filter. So I did two things, I had the fuel filter removed and cut it open to inspect it finding no sugar and I obtained test tubes and put 10 cc of gas in one, fuel injector cleaner in one and isopropyl alcohol in one then added two sugar granules. Using a hand magnifying glass I can easily see the sugar crystals still intact in all three tubes after 24 hours. So I now know the sugar does not dissolve in the gas or the additives I use and it is not getting out of the tank. Problem solved and myth of damaging power of sugar greatly diminished (a large amount could certainly clog the fuel pump intake).
Finally, if you drive a vehicle without a secure fuel filler like our '95 Caravan - get a locking gas cap.