Editor's Note: This is the second in a two-part series on the increased interest in hybrid vehicles.

If 2001 was, as Time magazine called it, the summer of the shark, 2006 could be christened the summer of the hybrid.

Hybrids don't star in the Al Gore-narrated global-warming documentary "An Inconvenient Truth." But you could say the cars, which run on a combination of gasoline and electricity, are part of the behind-the-scenes crew, getting mention on the film's Web site as a way consumers can help combat climate change.

One hybrid predecessor, General Motors' (GM) EV1, even has its own documentary this summer, titled "Who Killed the Electric Car?"

The New York International Auto Show and car dealers have given hybrids some serious exposure lately, too, and models such as the Toyota Prius and the Honda Civic hybrid are boasting long waiting lists for buyers. San Francisco and New York City are expanding their hybrid taxi fleets, with other cities considering doing the same.

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Even though doomsayers predicted the hybrid's shelf life would be short and sweet, it's still chugging along and even gaining momentum, like the "little engine that could" from the children's storybook.

Sky-high oil prices and an increased awareness of the energy and global-warming crises are helping fuel the hybrid's gradually increasing visibility.

"It's part of the popular culture now. You are going to see more offerings," said Aaron Robinson, technical editor at Car and Driver magazine. "Car companies that do not offer hybrids will be seen as behind."

With gasoline now selling at higher than $3-a-gallon in much of the U.S., hybrids are certainly getting more attention than ever before in their short lifespan. (Those sold in the United States are all less than 10 years old.)

Almost every major car company that does business in America is offering hybrids or has them in the works.

"Fuel is only going to get more expensive," Robinson said. "People are changing their buying habits as a result."

Toyota (TM), which has been a leader in the hybrid market, is offering a new gas-and-electric Lexus RX 400h and still has the hybrid Highlander, both of which are cleaner versions of the company's SUVs.

The Toyota Prius, perhaps the hybrid with the most futuristic, ooh-aah features — such as a rear-view camera that snaps images when the car is put in reverse, a laser "smart key" and a very space-age-looking dashboard — is on back order for at least 10,000 models, and has just passed the 500,000 units-sold mark since it first came out in Japan in 1997.

The Lexus GS 450h is a hybrid sports sedan, and the car maker's best-selling vehicle, the Toyota Camry, is now available in hybrid form too. Soon to come: a big, luxury fuel-and-electricity-powered Lexus sedan known as the LS 600h.

Toyota has also pledged to make a total of one million hybrid cars by the end of the decade.

"The hybrids have been profitable since very early on," said Toyota Motor Sales U.S.A. spokesman Wade Hoyt. "We're not losing money on it. It's not a charity operation. We see the market as expanding."

The Japanese car manufacturer isn't the only game in town when it comes to autos powered by gas and electric batteries, however.

Ford Motor Co. (F) offers the Ford Escape and the Mercury Mariner SUVs in the fuel-efficient forms, with plans for Ford Fusions and Mercury Milans to go hybrid by 2008.

Ford Motor Co. spokesman Monte Doran said sales of the Escape and Mariner hybrids were up 55 percent in the first five months of 2006.

"Ford is researching many different ways to deliver greener miles to consumers," Doran said. "Hybrids are a very important part of that: They deliver amazing improvements in fuel economy without sacrificing performance and utility."

Other car makers with hybrids in the works: Hyundai, Nissan and GM's Saturn and Chevrolet divisions, according to Robinson.

One Yellow Cab taxi driver in San Francisco has been carting passengers around in a Ford Escape hybrid since 2004 and can't remember what his life was like in the strictly gas-powered world.

"I love it. I wouldn't go back to a regular cab," said Paul Gillespie, the driver representative for the city's seven-member taxi commission. "It saved me between $4,000 and $5,000 in gas last year."

Gillespie said San Francisco has between 40 and 50 hybrid taxis on the road, and he hopes to see that number climb steadily.

"You're just so much less noisy and intrusive and stinky," he said. "It's a win-win situation — you're putting thousands of dollars in drivers' pockets in addition to reducing CO2 emissions."

Driving his hybrid SUV cab does feel different — "a little stiffer" and "not as cushy of a ride" — but his passengers enjoy and are intrigued by it, Gillespie said.

But though many models already on dealership floors are doing so well that would-be buyers have to take a number and get in line, regular gas-powered cars — the bigger, the better — still reign supreme, at least for now.

Some larger hybrids, like the Honda Accord and the Toyota Camry and Highlander, aren't selling as well as the Prius and the Honda Civic, according to Robinson.

"Not all hybrids are tearing up the sales charts," he said. "People are surprised about the staying power of SUV buyers."

In fact, Honda (HMC) is considering cutting back production of its Accord hybrid because sales of the vehicle have been slow since its introduction in late 2004, Dick Colliver, an executive vice president at Honda, said in April at the New York Auto Show.

He declined to provide exact figures, but overall Accord sales dipped 4 percent last year.

Ford recently retracted a production goal it had set of 250,000 hybrid vehicles by the end of 2010, upsetting some environmental and energy-conservation advocacy groups and garnering criticism for the American auto giant.

"With its chronic over-reliance on gas-guzzling trucks and SUVs and refusal to embrace the potential of GO [gasoline optional, advance plug-in electric] hybrids, Ford is running the risk of being left in the dust as companies like Toyota lead the next automobile revolution," the Rainforest Action Network said in a scathing statement released by the organization.

"Ford still sells the most oil-addicted fleet of vehicles in America."

Doran insisted that Ford remained committed to hybrids but had decided to invest in other cleaner-car technologies as well, including those incorporating alternative fuels like ethanol, diesel and hydrogen.

The decision to retract a set production number by a set deadline wasn't based on lagging hybrid sales, he said — since they have been strong for Ford this year to date — but on a desire to embrace several approaches rather than only one.

"Hybrids are not a silver bullet appropriate for every person and every situation," he said. "We're going to continue investing in hybrid technology and growing it where we think it makes sense, but in addition to that there are other technologies we're investing in that will meet different drivers' needs in different markets."

He said the existing hybrid technology gets its best fuel savings with city rather than highway driving and has weight-towing limitations (the Escape, for instance, can't tow more than 1,000 pounds) that don't necessarily work for farmers and others living in rural areas. Ford pickup trucks running on diesel, in contrast, can tow about 15,000 pounds.

"If you live in an urban market, the hybrid makes a lot of sense. For a farmer in the Midwest, frankly, a hybrid might not be the right thing," Doran said.

The fact that Ford was the first American auto maker to produce hybrid vehicles "speaks volumes" to the company's commitment to the electric-gas cars, he said. Currently there are about 26,000 Ford hybrids on the roads, with the plan of rolling out about 24,000 annually through 2007, then gradually increasing that number in subsequent years.

The company has also this year produced a quarter of a million ethanol vehicles, which run on E85 fuel, and has 30 Focus hydrogen fuel cell vehicles and a fleet of hydrogen E450 buses being tested on the road now, according to Doran.

As for Toyota, spokesman Hoyt said hybrid buyers still tend to "range from tree-huggers and environmentalists with the Prius to rich people who want the top-of-the-line Lexus hybrid" — but the Camry should appeal to "a more mainstream audience."

Even Disney (DIS) didn't deem hybrids or their all-electric forerunners sexy enough for its animated movie "Cars."

The original premise — an electric car tries to make its way in a gas-guzzling world — was scrapped in favor of the final storyline about a race car, according to the Internet Movie Database (IMDB.com).

Part of the ongoing struggle in the auto industry is the balance between vehicle performance and fuel efficiency, with the major players generally believing that the former is more appealing to American drivers than the latter.

That has led many of the SUV and other speedy hybrids to promise V6 or V8 performance with more miles to the gallon than a regular V6 or V8 car or truck.

But some insiders say that's a miscalculation, since most hybrid buyers seem to care more about efficiency than power — especially since they're paying premiums of up to $5,000 when they purchase a part-electric car over an all-gas one, even if they do get financing and other incentives for going hybrid.

Although larger hybrids do tend to get slightly better gas mileage and improved fuel savings than their completely gas-powered counterparts, the margin is sometimes fairly minimal, in part because of the focus on maintaining performance.

"The attempt to sell hybrids as a performance option is probably a misfire," Robinson said. "They will probably rethink their plans and offer hybrids strictly as a fuel-economy option."

At Toyota of Manhattan, for example, a hybrid Highlander on the floor was selling for $37,258, though its standard base price is $33,030, according to Toyota Motor Sales U.S.A. The EPA estimate on its mileage (which is always more than the real mileage) was 31 city and 27 highway.

The Prius, whose sticker price is $21,725, gets 60 in the city and 51 on the highway, according to the EPA.

Though plenty of ink has been spilled in the press about the science of the hybrid — and the eventual goal of replacing all cars that run on gas with those powered by hydrogen fuel cells — here's a refresher on how it works.

The cars run on both regular gasoline and on an electric battery, which takes over or assists the engine when the car is started, is stopped in traffic and at other times.

Though some people still have the misconception that hybrids are like other household appliances, the cars don't need to be plugged in.

Owners fill them up their tanks at the gas station like any other vehicles — and they likely won't feel any difference other than the initial sensation that the car has stalled when the electric battery kicks in. The vehicle is actually quiet because the noisy gasoline engine has shut off.

The cars also use a system known as regenerative braking, which relies on the motor to act as a generator and help stop the car.

Test-drive a Highlander hybrid, for instance, and you'll feel just like you're driving a regular Highlander or any smaller-size SUV. You might not even know you're behind the wheel of an environmentally friendlier truck if you don't happen to see the word "hybrid" on the side.

In the hybrid's early days — around 1999 or 2000 — consumers and automakers were hesitant to latch onto the trend in part because of the fear that the battery would die every so often and be expensive to replace.

But the oldest hybrids are still running on their original batteries, 100,000 miles or more later.

Robinson believes hybrids will one day become so common and so widely used that they'll just be another feature drivers can choose, rather than a totally different animal, the way they still seem now.

"We're going to stop thinking of hybrids as distinct vehicles," Robinson said. "Eventually it will probably be as common on the order sheet as air conditioning and automatic transmission."

FOX News' Michael Paranac contributed to this report.