Sugar does not dissolve in gasoline, so pouring sugar into a gas tank could clog up the filter of the car. If enough sugar is poured into the gas, it could disable the car, although this does not always happen. Pouring sand into a gas tank could have the same effect.Know More
A common rumor is that pouring sugar into a car leaves the vehicle completely disabled. This comes from the misconception that when sugar comes into contact with gasoline, a gelatinous substance is created that clogs up the fuel lines and disables the car. Despite the rumor, sugar and gasoline do not make a gooey substance. Rather, the sugar simply stays intact and does not dissolve in the gasoline.
Adding water to a gas tank, however, does disable a vehicle because gasoline floats on top of water. Pouring just a few cups of water into a gas tank causes the fuel pump, which is traditionally located at the bottom of a gas tank, to pump water instead of gasoline. According to HowStuffWorks, there are some cars that can turn water into fuel, but special conversion kits are required to do this, which is why adding water to most gas tanks renders the vehicles useless.