A fuel cell is an electrochemical conversion device. It produces electricity from fuel (on the anode side) and an oxidant (on the cathode side), which react in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the electrolyte remains within it. Fuel cells can operate virtually continuously as long as the necessary flows are maintained.

Fuel cells are different from batteries in that they consume reactant, which must be replenished, whereas batteries store electrical energy chemically in a closed system. Additionally, while the electrodes within a battery react and change as a battery is charged or discharged, a fuel cell's electrodes are catalytic and relatively stable.

TOP 1 - Toyota Prius



A family sedan, you can be best friends, like a dog. However, there are good dogs, like lassie save timmy, and bad dogs, which captures the gardens in addition to furniture and tearing. Here, then is a list of 10 Guai and medium-sized sedan, ranked by annual fuel costs, because when it comes to cars, no one is willing to buy a dog drink too much gas. In compiling our list, we have adopted the EPA's ratings, every year 15,000 miles -4 5 percent of the roads, 5 percent of the city driving - and the price of 3.51 U.S. dollars per gallon of gasoline consideration, and then select those we propose .

TOP 2 - Pontiac G6



Pontiac's mid-size sedan, the 3.5-liter, V-6 engine and four-speed automatic transmission is not as a sport as a vehicle manufacturers should we believe, but as a family hauler get the job done. Engine output is 219 hp and 219 lb.-ft. of torque. Handling is decent, audio, climate and other aspects of the control is a conscience, although drivers may not be as comfortable, as in other cars.

TOP 3 - Volkswagen Passat



Passat, this version of the Passat is turbocharged. That the right dash of fun and frugality. And 2.0-liter, 4-cylinder engine producing 200 horsepower and 207 lb.-ft. of torque through a six-speed manual Fed, which has a very good public services in the internal and smooth ride. The manual gearbox is standard, to provide automatic, but the notch that milestone.

TOP 4 - Ford Fusion



Slotted between the compact, focused and the larger Taurus, the Fusion is very easy to satisfy a small family. But trade and economic power, although 160 horsepower and 156 lb.-ft. of torque generated by the 2.3-liter, 4-cylinder engine is adequate day-to-day commuting. The best fuel economy, is to achieve and five-speed manual transmission.

TOP 5 - Mazda 6



Mazda decorated a well-off "zoom" from the same 2.3-liter, 4-cylinder engine used in the integration and UPS mileage. It's only 156 horsepower and 154 lb.-ft. of torque than the Ford 160 and 156 respectively, but good for almost 100 yuan of gasoline a year. Double wishbone front and rear suspension provide multiple high-spirited treatment. Miles is the same, regardless of transmission.

TOP 6 - Honda Accord



Honda's old car has been frugal, especially with four-cylinder engine. This year's 2.4-liter version produced 177 horsepower and 161 lb.-ft. of torque. Even base trim level to a lot of standard features, including audio controls in the steering wheel and six speakers, 160-watt sound system. The manual transmission model is relatively easy on gas than the automatic.

TOP 7 - Kia Spectra



With the lowest starting price here, the Spectra is quite the bargain. Drivetrain warranty is 10 years or 100,000 miles. The four-cylinder engine produces 138 horsepower and 136 lb.-ft. of torque. Interior materials are nicer than the price suggests, and it's nimble and utilitarian. We found the seats wanting and excessive engine drone at 75 mph or higher, but for a commuter car those might not be deal breakers.

TOP 8 - Chevrolet Malibu Hybrid



Much praise has been heaped on the new Malibu, and it's well deserved. Chevy has made a car worth consideration. Hybrid power comes from a 2.4-liter, four-cylinder engine and electric motor. Output is 164 horsepower and 159 lb.-ft. of torque fed through a four-speed automatic. A much-improved interior features sophisticated fun touches, such as modern gauges and mood lighting.

TOP 9 - Hyundai Elantra



Hyundai, as we've said many times, has come a long way from its rocky entry into the U.S. Improvements in quality and reliability have brought respect and buyers to the Korean automaker's vehicles. Case in point: the Elantra. With a 2.0-liter, four-cylinder engine producing 132 horsepower and 133 lb.-ft. of torque, places it third in a tough field. Six airbags and the seats are supportive and comfortable.

TOP 10 - Nissan Altima Hybrid



Nissan's Altima sedan has proven to be one of the company's more popular models. Equipped with a 2.5-liter, four-cylinder engine, assisted by an electric motor, this hybrid gets mileage north of 30 mpg. With 158 horsepower and 162 lb.-ft. of torque most drivers won't be wanting for power in their daily excursions. We like the upgrades inside and out in with the latest model, but found trunk space limited.