The government had sodium silicate put into the engines for their pointless and mass destruction of the cash for clunkers victims. Sugar water in gas would cause thousand of dollars of damage to an engine, but it probably would not destroy it beyond repair. Most damage would be to the injectors and the gas tank would probably need to be taken out and cleaned.
no, simple and true thats a no, it will make it cut out because of the water, the sugar will simply settle in the bottom of the gas tank, they have already proven this false on myth busters, if you really want to ruin a car, bleach is the way to go, expecially in the transmission fluid. Note: i am not responsible in any way for any actions caused by you, your friends or anyone else.
(this information is readily avaliable through the internet, expecially some really nasty ways to destroy cars)