Both KBB.com and the American Council for an Energy-Efficient Economy chose the Ford Focus Electric a Brad Berman for The New York Times Both KBB.com and the American Council for an Energy-Efficient Economy chose the Ford Focus Electric a “Best Green Vehicle” list contender.

Spring is in the air, and Earth Day is just behind us. Apparently, that means it’s green car choosing season, at least for the people who take the time to determine such things. But with the list of more environmentally friendly cars and trucks at an all-time high, choosing the best one can be tough.

Kelley Blue Book and the American Council for an Energy-Efficient Economy tried to make the choice simple by doing the choosing for consumers. Four vehicles made Kelley Blue Book’s 10 Best Green Cars of 2013 list and the council’s Greenest Vehicles of 2013 list.

Kelley Blue Book and its online arm, KBB.com, which published the study, rates the values of new and used vehicles, and the council is a Washington-based nonprofit financed by foundations, electric utilities and state and federal agencies. Both companies use different methods to calculate a vehicle’s green credentials, so it isn’t surprising that only four vehicles showed up on both lists.

Here’s a summary of what KBB.com editors said about the four 2013 models that were on both lists:

Ford Focus Electric

With Ford’s four-door hatchback as its foundation, the Focus Electric starts with a leg up. Toss in some cool features and an advanced powertrain that pairs a 107-kilowatt electric motor with a liquid-cooled lithium-ion battery and the result is a fun, practical runabout.

Honda Fit EV

The Fit EV shares most interior and exterior bits with its gas-powered counterpart. Though only 1,100 units will be produced, the lease-only Fit EV impresses as one of the most powerful and energy-efficient electric vehicles available.

Toyota Prius Plug-in Hybrid

With a combined fuel economy rating of 50 miles per gallon, it’s hard to believe that anything can top the Toyota Prius. Enter the Prius Plug-in, which adds 11 miles of all-electric driving.

Volkswagen Jetta Hybrid

The first gas-electric Jetta is a fun-to-drive European sedan that returns 45 combined m.p.g. and starts under $26,000. The Jetta Hybrid is a triple threat that lets you go green and have fun.

Ford’s C-Max was on both lists as well, but each organization chose a different version of the car. The C-Max Energi (a plug-in hybrid) was on the KBB.com list, and the regular C-Max hybrid was on the council’s list.

In an e-mail, KBB.com said it made its choices for their “standout mix of efficiency, range, innovation, affordability and overall appeal, as judged by the KBB.com editors.” The Nissan Leaf took the No. 1 slot “based in large part on its affordability,” while the premium-priced Tesla Model S came in second “on the strength of its desirability, surprising refinement and the longest range of any all-electric.”

The council’s method seems more scientific and holistic. It considers the emissions associated with a vehicle’s full life cycle — from manufacturing to disposal – and the fuel it uses, whether gasoline or electricity. The final calculation includes emissions from electricity generation used to recharge electric vehicle batteries as well as emissions involved in transporting petroleum.

All the vehicles on the KBB.com list are either hybrids, full electrics or plug-in hybrids. On the council’s list, the only nonhybrid and nonplug-in vehicles were the Scion IQ and Smart Fortwo (convertible and coupe).

By CHERYL JENSEN