The "hybrid" badges on an increasing number of vehicles carry a lovely green aura, but some are greener than others, according to the Union of Concerned Scientists.
"There may be a misconception that all hybrids are created equal," said Don Anair, a senior analyst with the organization.
Anair said automakers have a lot of flexibility in how to apply hybrid technology, including how much money they want to spend. That's why the nonprofit group came up with a hybrid score card to help consumers gauge hybrids based on fuel efficiency and value that ranks the vehicles in three categories, at hybridcenter.org/hybrid-scorecard.
Evaluating hybrids is more complicated than most consumers realize, making the score card helpful, said Karl Brauer, editor in chief at Edmunds.com. "I think going beyond EPA ratings is a good idea because there is more to it."
To measure environmental impact, the group looked at global warming based on fuel economy and emissions.
It compares the hybrid with its closest nonhybrid model. For example, the Ford Escape Hybrid is compared with the standard Escape. Where there is no direct counterpart, such as the Toyota Prius or Honda Insight, "we choose a model in the manufacturer's vehicle lineup that most closely matched the hybrid in vehicle class, size and acceleration," said Anair. "For the Prius, we chose the Toyota Matrix; for the Insight, we chose the Honda Fit; and for the Lexus HS250h, we chose the IS250."
The top model for environmental score was the Prius.
"Going from a conventional Toyota Matrix to a Prius reduces global warming emissions 44 percent. That's like trading in a Hummer H3 for a Mini Cooper," the study says.
Also ranking high was the Lexus RX450h, an all-wheel-drive sport utility, which, Anair said, shows the versatility of a well-designed hybrid system.
Hybrid value balances fuel-economy gains against the increased cost for the hybrid technology.
For example, "the hybrid system in the Lexus GS450h is $2,130 and reduces global warming pollution by 13 percent over a conventional model, giving it a hybrid value rating of ‘medium,'" the Web site says. "The hybrid system in the Civic Hybrid costs $3,983, but achieves a 31 percent reduction in global warming pollution, giving it a ‘high' hybrid value rating."
"Forced features" are basically extra equipment such as that required on the Milan hybrid.
"These are standard features on the hybrid that are otherwise optional on the conventional vehicle. On average they inflate the cost of these vehicles about $3,000," said Anair.
The best performers were the Honda Insight and Saturn Vue, available without any forced options.
The worst were the Chevrolet Tahoe Hybrid, GMC Yukon Hybrids and the Lexus LS600h L.
General Motors spokesman Brian Goebel said the automaker equips the hybrids with the packages that history shows customers are likely to buy on those vehicles.