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We are witnessing the launch of a new era of more fuel-efficient, less-polluting vehicles powered by technologies that aren't always familiar. If you're considering buying one of the new vehicles, you may well be concerned not only with how it handles but with how well it will hold up over time, what it might cost to maintain and if it really will be as good for the environment (and your wallet) as claimed. Fortunately, with a little information, the brave new world of greener alternative fuels and drivetrains is easy to grasp.

Use the overview below and the accompanying new vehicle slideshows to guide your purchasing decisions as you look for the best car that suits your needs.

Hybrid Cars

Hybrid gas-electric cars, which have been on U.S. roads for more than a decade, really aren't that complicated. Add an electric motor and rechargeable batteries to the conventional gas engine and see your efficiency increase by as much as 50 percent, with similar levels of reduction in emissions.

Due to the cost of the batteries and other systems, hybrids tend to cost a little more than conventional cars, but the so-called hybrid premium is constantly coming down. For high-MPG hybrids, most studies show that you'll recoup the extra cost during the course of ownership. The number of hybrid choices will grow to 55 models in the next five years.

Plug-in Hybrid Cars

A plug-in hybrid car is similar to a conventional hybrid vehicle -- both use a gasoline engine as well as an electric motor. However, a plug-in hybrid uses larger battery packs that can be recharged by connecting to common household electricity. Plug-in hybrids can be driven for long distances -- from a few miles to as much as 40 miles -- without using any gasoline. The Chevy Volt is the first mass-produced plug-in hybrid, but more models are on the way from Toyota, Ford, Hyundai and others.

Plug-in hybrids have many of the benefits of electric cars, without the biggest drawback: limited driving range. When the juice runs out of the battery in a plug-in hybrid, it's no problem. The car will drive just like a conventional hybrid, until your next opportunity to plug in.

Electric Vehicles

Unlike a hybrid car -- which is fueled by gasoline and uses a battery and motor to improve efficiency -- an electric car is powered exclusively by electricity. Electric cars produce no tailpipe emissions, reduce our dependency on oil, and are cheaper to operate.

EVs have fewer moving parts and systems and therefore have lower maintenance costs. They also come with generous warranties to provide consumers maximum comfort with adopting unfamiliar technology.

Of course, the process of producing the electricity moves the emissions further upstream to the utility company's smokestack. Yet on average electricity can cut carbon pollution to half that released by a gas-powered car -- even less in areas with cleaner generation, though more in areas that rely more on dirty coal power plants.

Besides driving range -- which can vary between 60 and 120 miles -- the biggest concern with electric cars these days is cost. The purchase price of electric cars can run quite a bit higher than similar conventional cars, but between generous government incentives, fewer maintenance costs, and the lower cost per mile for electricity compared to gasoline, the new breed of electric cars have a lower cost of ownership. Remember: no tailpipe emissions and no trips to the gas station.

High Fuel Efficiency, Conventional Gasoline Engine Cars

A car with a smaller engine will almost always use less fuel. The good news is that gas-sippers are no longer stripped down econoboxes lacking comfort, amenities, safety, and performance. Thanks to advances in gas-engine technology -- like direct injection, turbocharging and variable timing -- press reports indicate that this new breed of fuel-efficient cars is comfortable, stylish and fun to drive. They often can be more affordable than the better known hybrids, and require no compromises in terms of driving behavior or safety. A growing number of them are breaking past 40 mpg on the highway, giving hybrids a run for their money.

Diesel Vehicles

Diesels operate more efficiently by igniting fuel with high compression ratios and high combustion temperatures. As a result, diesel vehicles attain better fuel economy than their gasoline counterparts. In addition, a gallon of diesel fuel contains about 10 percent more energy than a gallon of gasoline. These factors help modern diesels achieve roughly 25 percent higher fuel economy than their gasoline counterparts.

The cleanest of the current crop of diesel vehicles are now available in all 50 states, thanks to innovative new pollution control equipment that meet EPA's strict pollution standards. Diesel vehicles now account for nearly half of all new vehicle sales in Europe, and a small but growing market share in the U.S.

Ethanol Flex-Fuel and Biodiesel Vehicles

Biofuel are a tricky subject. In theory, cars that run on fuel that is grown in the ground -- rather than drilled and extracted from it -- should be better for the environment. But most studies show that corn ethanol, the most common form of biofuel in the U.S., is a net loser of energy, has questionable emissions benefits, and has a negative impact on food prices. Then, there's the problem of finding a station that offers E85 -- a blend of 85 percent ethanol and 15 percent gasoline -- and the fact that E85 carries less energy in a gallon and therefore can end up costing more for a mile of travel.

Biodiesel, which runs in diesel-engine vehicles, can have a better eco-profile -- that is, if it comes from recycled sources, like used restaurant oil. But new diesel cars cannot use high blends of biodiesel because the pollution control equipment is too sensitive and biodiesel pumps are few and far between.

last revised 1/25/2011