Yellow Clean Air Vehicle decals that have allowed hybrid cars to qualify driving in the carpool lane will expire after this Friday, July 1.

This incentive program, which was limited to the first 85,000 applicants of qualifying hybrids, succeeded in making hybrid vehicles popular in the Bay Area as people were attracted to the shorter commuting time that the program guaranteed.

The white Clean Air Vehicle decals, available until January 1, 2015, are similar to the yellow ones but apply only to cars that are certified as pure zero emissions vehicles, meaning cars that are electric, hydrogen-powered, or compressed natural gas vehicles.

Another Clean Air Vehicle decal will also be issued to 40,000 applicants to purchase or lease cars that meet California’s advanced technology partial zero emission vehicle requirements starting January 1, 2012 until January 1, 2015.

The DMV mailed out individual letters to all registered vehicle owners to remind them of the change and sent out a warning that single drivers in the High-Occupancy Vehicle (HOV) lane will be cited, according to a DMV press release.

The program was born out of the need to find ways to improve air quality and ease freeway congestion, explained the press release. Both lawmakers and transportation experts agreed that utilizing the previously underused HOV lanes for environmentally friendly vehicles would be a “win-win.”

Senator Fran Pavley, who sponsored the incentive program in 2004 as well as its conclusion this week, was reported by the San Francisco Examiner to have said, “It’s time for [the program] to end.”

“We believe it’s been a huge success in incentivizing people to purchase hybrids, which, at the time this program started, were not very well known,” she said.

Prius owners weren’t happy with the arrangement.

On June 26, there was reportedly a “Prius Party” in San Jose where several hundred drivers ceremoniously scraped off their stickers.