Plug-in hybrids stretch your fuel dollar even farther. You can plug your car into an electrical socket to charge it, and the car will run on that cheaper electricity alone for a while -- and when that runs out, there's a gas engine to take you as far as you want to go. With a plug-in hybrid, you don't have to worry about getting stranded (a common concern with pure electric cars, discussed below).
Plug-in hybrids cost more than regular hybrids up-front -- but you can get up to a $7,500 federal tax credit for them. Many states offer thousands of dollars' worth of tax credits, too -- up to $6,000 in Colorado, $4,000 in Illinois, $3,500 in Pennsylvania and $2,500 in California, just to name a few.
The 2012 Chevrolet Volt (Base MSRP: $39,145) is the best plug-in hybrid you can buy, according to reviews. This four-passenger hatchback can run on electricity for an EPA-estimated 35 miles (two top expert tests both ranged from 20 to 50 miles, depending on weather and driving style). So if your commute doesn't exceed that, you could drive for weeks or months without burning a drop of gas.
Jay Leno did, for almost a year. "I've never had to put gas in it yet," Leno told The New York Times, after commuting in his Volt every day for 11 months. "They gave it to me with a full tank of gas ... I've used less than half of that."
The Volt runs on its electric motor, which cranks out a healthy 149 horsepower and 273 pound-feet of torque. You can recharge it by plugging it into an electrical socket (allow 10 hours on a regular 120-volt outlet, or four hours if you've installed a 240-volt charge station) -- or the 1.4-liter gas engine will kick in and act as a generator. Expect 37 mpg if you're running on gas. On electricity, the Volt gets the equivalent of 94 mpg, according to the EPA.
Aside from its techno-wizardry, testers say the Volt feels like a nice car -- solid, smooth and quiet, "with materials that seem to be the best yet from recently improved Chevrolet," Edmunds.com says. But the two back seats, separated by the big battery pack, crowd adults. Cargo space behind them is just 10.6 cubic feet, although the seats do fold.
This year, General Motors replaced Volt owners' 120-volt charging cords with thicker cords, after some owners complained that the original cords overheated and melted. GM also beefed up the Volt's battery protection after a Volt caught fire several weeks after a government crash test; the National Highway Traffic Safety Administration investigated and concluded that the Volt is no more likely to catch fire than other cars.
The 2012 Toyota Prius Plug-in Hybrid (Base MSRP: $32,000 to $39,525) goes head-to-head with the Volt. It's roomier -- holding five people comfortably, with 21.6 cubic feet of cargo space -- and it gets better mileage from its gas engine (50 mpg, just like the regular Prius). But it can't drive nearly as far on electricity as the Volt (about 11 miles, according to the EPA) and some testers say the Prius Plug-in's gas engine actually kicks on earlier than that, if you're not feather-light on the throttle. The Volt, meanwhile, can zoom up to 100 mph gas-free, with plenty of muscle and a natural drive feel, unlike the slower, duller Prius Plug-in. The Volt qualifies for a bigger federal tax credit, too -- up to $7,500, versus $2,500 for the Prius Plug-in -- which largely erases the price difference.
If money's no object, the 2012 Fisker Karma (Base MSRP: $102,000 to $116,000) is "arguably the most breathtaking sedan of this new millennium," Autoblog.com's Damon Lavrinc says, and other critics agree. The plug-in hybrid Karma four-seater is the brainchild of car designer Henrik Fisker, who refused to let engineers and accountants mess with his concept car's racy-looking, voluptuous body. Unfortunately, that makes for minuscule rear seats and an even tinier trunk, and some owners -- including ConsumerReports.org, which bought a $108,000 Karma to test -- say the car started breaking down practically the moment they bought it. Like the Volt, the Karma qualifies for up to a $7,500 federal tax credit.
Pure electric cars run solely on plug-in power. They can carry you farther on electricity than plug-in hybrids can -- about 60 to 75 miles, versus 35 miles for the Chevrolet Volt (discussed above) -- but there's no backup gas engine.
"Running out of juice isn't the same as running out of gas," ConsumerReports.org cautions. "No one can come to your aid with a gallon of electricity to tide you over, and knocking on a neighbor's door pleading for an electric outlet may not be well received. If your EV runs out of get-go, it means calling a tow truck."
Still, if you need a car only for short trips, electric cars are the most efficient way to go. They get the equivalent of about 100 mpg -- or more -- with electricity costing far less per mile than gas. Like the Volt, electric cars also qualify for a $7,500 maximum federal tax credit, plus additional tax credits in some states.
The 2012 Nissan Leaf (Base MSRP: $35,200 to $37,250) is experts' favorite electric car. "If it makes sense for your lifestyle and you're excited at the idea of owning a full-electric vehicle, the 2012 Nissan Leaf won't disappoint," says Edmunds.com.
That's because -- aside from its eerily silent electric motor -- the Leaf drives pretty much like a regular small hatchback, testers say. It seats five (four quite comfortably, although three across the back is a squeeze) in a nicely finished and equipped cabin, with a serene ride and solid handling.
But the Leaf gets vastly better fuel economy than a regular car -- the equivalent of 99 mpg, the EPA says. Thanks to 207 pound-feet of torque, the Leaf gets off to a quick start. Acceleration tapers off at highway speeds, but the 107-horsepower Leaf builds to 60 mph in a perfectly adequate 10 seconds -- about the same as the typical automatic-transmission subcompact car, Edmunds.com says.
Nissan says the Leaf can go 138 miles on a single charge in ideal conditions -- but the EPA says 73 miles is more like it, with normal driving. It takes seven hours to fully charge on a 240-volt home charging station, or 20 hours on a regular 120-volt outlet. You can add a special port to your Leaf to take advantage of public 30-minute quick-charge stations, but these are rare.
The 2012 Ford Focus Electric (Base MSRP: $39,200) is just as comfortable and easy-driving as the Leaf in tests, slightly more efficient (105 mpge) and longer-range (EPA-estimated 76 miles per charge) -- plus it charges twice as fast (on a 240-volt outlet) and it looks exactly like a regular Focus hatchback. That's a bonus, critics say, because the Focus is a handsome car -- and because they get tired of being pointed and stared at in the bulbous Leaf.
The 2012 Mitsubishi i (Base MSRP: $29,125 to $31,125) is the cheapest, most efficient electric car you can buy (estimated 112 mpg). Unfortunately, critics say, you get what you pay for: The i-MiEV feels cramped and cheap in tests, and it can't go as far on a charge (EPA-estimated 62 miles).
No pollution comes out of an electric car -- while you're driving it. But that electricity came from somewhere. If it came from a power plant that burns coal or natural gas, then your electric car just indirectly spewed pollution into the air.
So which is cleaner, an electric car or a fuel-efficient gas-burner? Usually, the electric car -- but it depends on where you live, according to the U.S. Department of Energy.
To crunch the numbers yourself, try the calculator at the U.S. Department of Energy's website. It lets you plug in different cars, gas prices and the number of miles you normally drive, to check whether car A will cost less to run -- or pollute less -- than car B.
For UCS's full April 2012 report, "State of Charge," visit the Union of Concerned Scientists' website. Check out the color-coded U.S. map, and you'll see at a glance whether you live in a "clean"-electricity region.