"As motorists cut back on their driving and buy more fuel-efficient cars, the government is taking in less money from the federal gasoline tax.
The result: The principal source of funding for highway projects will soon hit a big financial pothole. The federal highway trust fund could be in the red by $3.2 billion or more next year.
The fund, set to finance about $40 billion in transportation projects next year, is increasingly strained. [L]awmakers must figure out whether the 18.4-cent-a-gallon federal gasoline tax, which helped bring in money when fuel-hungry SUVs were hot, is still a viable way to fund transportation projects amid heightened concern about gasoline prices, U.S. dependence on foreign oil and global warming."