If you’re more than a little confused by California’s rules allowing clean cars into the much-prized diamond lanes, join the club. The state DMV and the California Air Resources Board haven’t done a great job of clarifying matters, either, though they’re getting better.

Things will come to a head in the new year with a new set of stickers for green cars (plug-in hybrids and battery electrics), and it’s causing some anxiety for state motorists. So here’s some clarification, in plain English.

Starting January 1, 2019, California will issue its new stickers, using an as-yet undetermined evaluation system and sticker color. At that time, all of the existing stickers—white, green, and red—will become inoperative, according to Karen Caesar, spokeswoman for CARB.

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John Swanton, a CARB air pollution specialist, said that the new program should be revealed in October or November. CARB has said that “the vehicle eligibility requirements for the new decal mirror those used for the current white and green decal programs.”

Even though the green and white stickers originally applied to different types of low-emission cars, Swanton says the colors have been used interchangeably as California has wound down its current program.

“People fixate on the color, but it makes no difference now,” Swanton said.

Green HOV-Lane Sticker

Green HOV-Lane Sticker

Drivers who were issued red, green, or white HOV stickers in 2017 or 2018 can apply for the new decals after January 1, 2019 that will be valid for three years.

People who buy new cars after January 1, 2019 and apply for a sticker will get to use the diamond lanes for up to four years. The rule for new vehicles is that a decal issued after January 1, 2019 expires after three full years plus “the partial year from when the decal was issued.” That rule gives motorists an incentive to buy early in the year, Swanton explained. All decals expire on September 30, 2025.

If you buy a used green car, it’s eligible for a new sticker only if it never had one.

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By the way, if you have a yellow sticker on a Prius or other hybrid vehicle, it’s been meaningless since July 1, 2011. Hybrids don’t qualify anymore, and using a diamond lane with an expired sticker (or similar HOV abuse) subjects motorists to a $375 fine, plus court costs.

People have also bootlegged the stickers, but that leads to a big fine, too. A poster on Reddit speculated about using a fake sticker and was told to forget it: “Highway Patrol absolutely does stop and check these, and the penalty is similar to using fake vehicle registration stickers; basically, you get a big hefty ticket, your car gets impounded, and you have to pay both the ticket, court fees and all the tow fees to get your nice new car back.”

— Jim Motavalli