The hotbed of electric cars so far has been the U.S. West Coast. California, of course, is the leader, with its zero-emissions vehicle mandates. Going up the coast, the selection—and sales—get steadily thinner, but remain conspicuous.

Now the Evergreen State, which has a strong electric-car presence even though it does not follow California zero-emissions mandates, is about to lose its biggest incentive for plug-in car buyers: the sales tax exemption.

The latest two- year program, started in July 2017, was so successful that it is scheduled to run out of credits at the end of May after 11 months.

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The state program allowed for sales tax exemptions for non-luxury plug in cars, but the legislature limited the number of exemptions to 7,500 over the two years. Now so many drivers have bought plug-in cars that those exemptions are scheduled to run out by the end of May. .

This is the second round of the program in Washington State, and it's not clear if there will be a third. It applies to any car powered by a clean alternative fuel, including hydrogen or natural gas, or that gets at least 30 miles of range from electricity, but it includes price limits to prevent people from getting a discount on luxury cars. Buyers don't pay sales tax on the first $32,000 of the purchase price of a clean car up to a total price of $42,500. No exemption applies to cars more expensive than that.

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A bipartisan bill to extend the sales-tax exemption was introduced in the state legislature in January, but has been stuck in committee since March. Legislators still have 30 days before the exemption expires, so perhaps it will survive Virginia's fate (link, above).

If you live in Washington State and are in the market for a plug-in or alternative-fuel car, act quickly. We'll keep our eyes on this story for those of you who need to wait.