SEATTLE -- The mayor wants to transform the city's gas-guzzling taxis into eco-friendly rides. But some taxi drivers say going green will cost them too much green.

Under Mayor Greg Nickels' climate-friendly cab plan, drivers will have to trade in their cabs for a $21,000 hybrid counterpart. That number isn't sitting so well with the city's cab drivers.

He says the switch could save the driver roughly $10,000 in gas over the life of a cab, and help save the environment for generations to come.

A regular taxi gets 18 miles per gallon while a Hybrid Prius taxi gets 44 miles.

"It just doesn't matter if our cabs are orange, yellow or grey. We think they should all be green," Nickels said.

As a part of his plan, the mayor wants to put more than 300 additional taxis to work on Seattle's streets and also regulate how much owners can charge to lease their cabs to other drivers.

The measure is headed to the City Council.