More than half of the states offer motorists incentives for buying hybrid cars, whose gas mileage vastly surpasses that offered by cars with conventional engines, according to the Denver-based National Conference of State Legislatures.

The US government, eager to cut the nation's dependence on crude oil imports, offers tax credits ranging from US$1,550 to US$3,150, depending on the make and model of the hybrid car, according to an IRS spokesman.

The federal tax agency's list, which is not yet complete, appears on the Web site: http://www.irs.gov/newsroom/article/O,,id=157557,00.html

Some states offer the incentives to help them meet air quality standards, said Kate Burke, an analyst with the National Conference of State Legislatures.

Pennsylvania's Democratic governor, who is running for reelection, has proposed the richer hybrid car rebates as part of his plan for spending a US$260 million surplus, according to a statement he released late on Tuesday.

"With current fuel costs and our nation's dependence on foreign oil, the governor is keenly focused on encouraging alternate energy choices like the purchase of hybrid cars," Rendell spokeswoman Kate Philips said.

Rendell also asked the Legislature to enact two one-week sales tax holidays for consumers who buy energy-efficient appliances, from ceiling fans to dishwashers, along with business and family tax breaks, Philips added.

A number of states also offer hybrid motorists another break that is especially attractive to solo commuters -- the freedom to use high occupancy vehicle lanes without carrying passengers, according to the hybrid car Web site.

Corn-rich Illinois gives motorists rebates of as much as US$4,000 for switching a vehicle to burn an alternate fuel.