Allow price fluctuations! Great story here by Stossel.
The key point:
"Today, some car owners wait in line just to top off their tanks. If gas stations could raise prices, many of those drivers would wait, and drive less. Drivers who really need gas would be able to get it. At the same time, entrepreneurs would rush gasoline to gas stations that have the highest prices. The lines would quickly vanish, and prices would come back down."