Researchers from the University of Iowa Public Policy Center have developed a system for charging drivers federal taxes by the distance traveled rather than on gallons of gas purchased. The study is being conducted with 2,700 drivers from states like Maryland, Texas, Iowa and California to gauge public reactions and experiences with the system. The basis for the study is the declining tax dollars being paid for car use in the States; as fuel prices rise, cars get more efficient, and alternatives like ethanol and hybrids gain ground, our 18.4-cents-a-gallon tax on gas (which was set in 1993) remains static, thereby making it harder for The Man to get paid. Eventually, the government will have to find another way to generate tax dollars from drivers -- and researchers think this might be it. Instead of paying a constant fee on the fuel we purchase, drivers cars are equipped with a taxi-like meter, and users will be given a monthly bill for the miles that they've driven. We can only hope this is avoidable, perhaps due to the spontaneous existence of a free, plentiful, environment-friendly fuel source... or another revolution.