(MONEY Magazine) – Americans are all in favor of saving fuel, as well as the planet. And we're fascinated with gee-whiz hybrid cars like the Toyota Prius that pair electric and gasoline power to boost mileage and cut emissions. Just don't ask us to pay much extra for either benefit. Or to trade SUVs for a dawdling economy car.

Since the seminal Prius was launched in 1997, hybrids have been as much social statement as transportation--trendy accessories for Hollywood stars, early adopters and card-carrying Greens. But what if you could buy a hybrid version of your favorite family mid-size? Or a luxury SUV? Or even a pickup truck?

We're about to find out: A fresh batch of hybrids is coming, most based on car and truck models that consumers already know and love. And if the latest hybrids can look, drive and last like conventional models, more mainstream buyers may give them a shot.

(Contrary to what many people assume, hybrids never need to be plugged in, because their batteries recharge while you drive. The batteries' energy still relies on gasoline; you just fill 'er up and drive.)

The technology--and how seamlessly it works--is undeniably impressive. Yet for most shoppers, the buying decision will still hinge on a core pocketbook issue: Have these virtuous vehicles become good enough to justify spending thousands of dollars more?

THE NEXT WAVE

The first big test comes in late September, when Toyota's second-generation Prius goes on sale. The improvements are striking. Gone is the frumpy styling, replaced by a fuel-saving teardrop shape that's among the most aerodynamic in the auto world. A substantially larger cabin sneaks the Prius into mid-size territory, though it's still smaller than the Camry or Honda Accord. Fuel economy rises from 48 miles per gallon to 55 mpg, which Toyota says is twice the mileage of its nearest mid-size competitor. And while the outgoing Prius was a tortoise, the new model will accelerate from zero to 60 mph in just over 10 seconds, barely trailing a four-cylinder Camry.

How do you make a car bigger, faster and more fuel efficient? With what Toyota calls Hybrid Synergy Drive, a system the automaker plans to offer in a full range of eco-friendly cars and trucks in coming years. It employs the hybrid's familiar gas/electric tag-team strategy (see "How Hybrids Work," below), but with new sophistication. A stronger electric motor provides go-power to supplement the compact, 1.5-liter gas engine. Go easy on the pedal, and the Prius will switch seamlessly between gas and electric power to maximize economy; mash the gas, and it engages both power sources for faster acceleration.

The new Prius achieves California's environmentally strict Partial Zero Emissions Vehicle status, along with the state's Super Ultra Low Emissions Vehicle rating, meaning that it's 90% cleaner than the average new 2003 model.

COSTS VS. BENEFITS

The caveat is that you'll still pay a stiff premium for hybrid technology. Toyota will keep the 2004 price close to the current model's $20,480 base tag. Fine, but that's still about $5,000 more than Toyota's top-of-the-line Corolla LE--perhaps the world's best compact car, which delivers 38 mpg on the highway.

Don't expect savings on gas to make up for that difference. A 37.5-mpg compact car uses 400 gallons of gas to cover 15,000 miles. Even assuming a lofty $2 a gallon, that's $800 a year for fuel. So if hybridizing the same car could boost mileage to 55 mpg (an optimistic 47% improvement; engineers peg actual gains much lower), you'd save about $250 a year at the pump. At that rate, you'd have to drive the hybrid for 16 years and 240,000 miles to offset the typical price premium of about $4,000. AutoPacific analyst Jim Hossack figures that unless gasoline soars to $4 or so a gallon, most consumers will find hybrids' price too dear. A federal tax credit is available to hybrid buyers, but it shrinks each year and expires in 2006.

In addition, there's the newness and complexity of hybrids' batteries, dual power sources, electronics and computer controls, raising numerous questions about ease of repair and long-term resale value. Toyota engineers are confident that the Prius' batteries, backed by an expanded 150,000-mile warranty, will last the life of the vehicle. But they acknowledge that hybrids simply haven't been around long enough to know for sure. Replacing the batteries could prove enormously expensive, and even if the automaker eats the cost, that would eventually be reflected in a lower resale value. Again, hybrids may answer a higher calling, but they're not yet persuasive on the bottom line.

NEXT STOP: TRUCKS AND SUVs

Of course, people buy cars for all kinds of impractical reasons, not least being the statement they make. If fuel economy does become fashionable, tidy-sized hybrids could become the latest cool car to display in the driveway. But here and now, SUVs, pickups and minivans account for more than half of sales. Car sales are flat, and hatchbacks are about as popular as French politicians.

Enter the Ford Escape HEV, which will be the first "full" hybrid truck when it arrives next summer. (GM and Dodge pickups with what are called "mild" hybrid systems--less-costly technology that delivers only a few extra miles per gallon--arrive later this year.) Ford's frugal take on the popular compact SUV is expected to accelerate like the V-6 model and deliver 35 to 40 mpg in city driving, compared with 18 mpg for the gas version. Available in four-wheel drive, the Escape will match the Prius' emissions standards, and its driving range of 400 to 500 miles blows away the standard Escape. Expect to pay a hefty premium over the gas-only Escape, whose base price ranges from $18,710 to $26,910. But that may be beside the point: This kind of truck could provide perfect cover for Americans who love their SUVs but are troubled by lousy mileage.

In the same vein, next fall brings a hybridized Lexus RX330, the model that kicked off the craze for carlike SUVs. A pessimist might suggest that buyers who care about saving money or fuel won't be shopping for a $40,000 luxury SUV to begin with. Anticipating that argument, Toyota plans to market the RX330 hybrid not just as eco-friendly but as the top-of-the-line model. Turns out, hybrid power can be as fast as it is frugal, says Toyota division general manager Don Esmond: The RX330 will seek to deliver V-8 acceleration with the fuel mileage of a compact car.

WINKING AT SACRIFICE

Such mixed messages show that hybrid backers know what they're up against. Winning over environmentalists was the easy part: To them, a hybrid car is an all-natural, feel-good purchase.

But what about people who don't feel bad? In some surveys of auto buyers, fuel economy barely appears as a priority. Overall, cars driven by Americans have seen average mileage decline to 20.8 mpg, down from a peak of 22.1 mpg in the late 1980s. Over that time, the average vehicle has become much heavier, and engine improvements have nearly doubled horsepower while fuel economy goes wanting. Blame the automakers' profit priorities if you must, but it's American consumers who have spurned efficient small cars in favor of bigger, faster, greedier SUVs, luxury and performance models. Until that fact changes, automakers aren't about to make the mistake of Jimmy Carter, who famously donned a cardigan and dared to ask America to conserve--to sacrifice--in the face of dwindling oil and gas reserves.

Instead, the marketing for the latest green machines will extol the environmental yet wink at sacrifice. Fuel economy and cleaner emissions are going to be likened to icing on the cake--or as Toyota's Esmond puts it, with regard to the Lexus RX330, "a hot fudge sundae with fewer calories." Ford's pitch for the Escape HEV, meanwhile, says the truck requires "no compromises" from owners. It'll have to. Because for most consumers, sacrifice is a subject for cocktail parties--not car shopping.