Incentives to get drivers to buy highly fuel-efficient cars have taken many forms, one of the most popular being single-occupant access to carpool lanes on crowded freeways.

Hybrid-electric vehicles were some of the first beneficiaries of these policies, but now they're being elbowed aside by zero-emission vehicles powered by electricity or hydrogen.

2011 Toyota Prius

2011 Toyota Prius

And now a new amendment to a proposed U.S. Senate bill that renews highway funding for six years has made the demotion official.

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According to The Detroit News, Senator James Inhofe [R-OK] proposed the amendment, which would forbid states to include hybrid vehicles in new carpool-lane access programs funded by the bill.

Instead, vehicles eligible for access to High-Occupancy Vehicle (HOV) lanes with just a single person inside would be limited to electric cars--those that run some or all of the time on battery power alone--hydrogen fuel-cell cars, and natural-gas vehicles.

The portion of the Federal highway code that permits such single-occupancy incentives is set to expire in 2017. Inhofe's amendment extends the expiration date at the same time that it eliminates hybrid vehicles from eligibility.

ALSO SEE: CA To Hybrid Drivers: Sorry, We're Just Not That Into You--Any More

The move essentially follows California's lead.

CA 'Access OK' Clean Air Vehicle carpool lane sticker

CA 'Access OK' Clean Air Vehicle carpool lane sticker

Starting in 2005, that state issued 75,000 "yellow stickers" to registered owners of Toyota Prius, Honda Insight, and Honda Civic Hybrid cars.

But it let those stickers "sunset" on July 1, 2011, and started a new program that provided "green stickers" to owners of range-extended electric cars and plug-in hybrids instead, which are good through 2018.

The supply of 40,000 green stickers has now been exhausted, though legislation is pending to boost the supply to 85,000.

MORE: CA Electric-Car Incentive Update: Funds Run Out, Green Stickers Gone

It also has a separate program of "white stickers" for owners of battery-electric, hydrogen fuel-cell, and natural-gas powered vehicles.

Meanwhile, prospects for passage of a new highway funding bill remain uncertain as a highly contentious mid-term election approaches.

Funding for the Department of Transportation could run out as soon as late August.


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