New car buyers in the state of Washington are going to get a break on their sales taxes when they buy some vehicles that run on alternative fuels.

This story from the Seattle Post-Intelligencer says it’s expected to save them $18.6 million over the next couple of years and is designed to get people to trade in their old gas guzzlers (although, high gas prices ought to be enough incentive, right?):

The tax break, which takes effect Jan. 1, applies only to new vehicles. It also only covers cars and trucks getting at least 40 highway mpg, which includes the Prius and hybrid Honda Civic, but not the Toyota Camry or hybrid SUVs.

“What this law does is it helps people save some money to get them to choose a car that’s more fuel efficient — and that’s a good thing,” said Don Fahnestock, an owner of The Green Car Co., a Bellevue business that sells extra fuel-efficient vehicles.

The tax break (9.3 percent in the Seattle area) covers vehicles that run on natural gas, propane and hydrogen, as well as “neighborhood electric vehicles” or “medium speed vehicles” (street legal, but can’t go faster than 35 mph).

The incentive is for all vehicles purchased in and out of state between Jan. 1, 2009 and Dec. 31, 2010. Washington residents can take still buy a car before the end of this year to get the sales tax exemption. They just have to wait to register and title their vehicles until after the first of the year.