The family muscle car

To describe its current marketing approach, the auto industry might want to dust off the old slogan "power to the people." Detroit and the foreign automakers are in a horsepower war not seen since the muscle-car era of the 1960s. While the most powerful cars of that time cranked out about 300 horsepower by today's standards, this year's sports cars pack an even greater wallop. The Mustang Cobra, for example, boasts 390 horsepower. The Dodge Viper, a car best known for pushing the envelope, belts out 500.

And that's just sports cars. Family sedans and SUVs are following the trend, blowing right past those old muscle-car levels.

"Consumers always want more power," says Bob Lutz, head of product development at General Motors and a man widely recognized as one of the biggest players in the automotive industry.

That much was clear at this month's North American International Auto Show in Detroit. Advancing an age-old crosstown race, Ford and Chevy each debuted family-sedan concept cars packing 590 and 420 horsepower, respectively. Nissan introduced its new Maxima sedan with "260 horsepower plus." (A mere four years ago, its 190-horsepower Maxima was one of the most muscular sedans on the street.)

Also across the Pacific, Mitsubishi and Subaru each introduced street versions of their compact racing sedans - the Evolution VIII and the WRX STi - boasting 280 and 300 horsepower, respectively. Infiniti offers two luxury family sedans - the M45 and the Q45 - each with a 345-horsepower V8.

The Europeans have eagerly joined the fray: BMW, Mercedes-Benz, and Audi each have small sedans with between 330 and 350 horsepower. Mercedes-Benz offers a 500-horsepower mid-size sedan. And Porsche has rolled out its long-heralded 440-horsepower, twin-turbo SUV, the Cayenne. At the top of the pile is Cadillac's 1,000-horsepower luxury car, the Sixteen (as in 16 cylinders).

It's enough to leave even a dyed-in-the-wool car guy slack-jawed in wonder. These were professional drag-strip numbers only a few years ago.

"Power feeds off our emotions. Most drivers like to be able to push the pedal to the floor and get a little thrill," says Chris Cedargren, principal of Nextrend, an automotive consultant firm in Thousand Oaks, Calif.

Still, the question on many observers' minds at the Detroit show was, "How much is too much?"

It's hard to quantify. After all, some family sedans with power ratings on the low side of 200 feel plenty peppy. But other heavy, 300-plus horsepower cars still feel slow.

Today's horsepower wars are enabled by advances in technology - and to some degree, demanded by them. Aside from behemoth SUVs, even today's small cars are weighed down with enough electronics to launch several moon missions. Add to that the heavy copper wiring found in today's cars and you wind up with weighty vehicles that need more power to get going.

Fortunately, advances in basic internal-combustion engines have allowed engineers to extract more power from a gallon of gasoline. Those advances gave automakers a choice: Produce cars with the same power using less gas, or build vehicles that boost power and burn the same amount of fuel.

Many automakers have chosen the latter.

Not everyone is thrilled by the trend. The Insurance Institute for Highway Safety (IIHS), for example, has protested car ads that "glorify speed."

"In general, vehicles with a lot of horsepower encourage fast driving, and speeding is a leading factor in fatal crashes," says Russ Rader, spokesman for the IIHS.

The move to more power has also upset environmental activists.

According to Dan Becker, a lobbyist for the Sierra Club, the average miles- per-gallon rating of all new cars actually sold off dealer lots today is declining. A lot of that decline, he says, "is because horsepower is increasing, and a lot of it is [heavy] trucks with big horsepower. This Cadillac [Escalade] and other outrages are really abominations."

Mr. Becker is also upset by the fact that automakers know how to build cars with greater fuel efficiency than ever before and aren't building them.

While such voices for moderation are growing, the American public keeps speaking with its pocketbook. Its collective vote: More power!

Car buyers crave power because they want increased acceleration, especially from a stop. As a result, engineers have designed cars with large engines that burn lots of fuel.

Automakers are now caught between that public demand for power and calls by others for greater fuel efficiency.

This year, some carmakers showed they hope to bridge the gap, displaying concepts that deliver lots of power, but do it more frugally. High-powered cars that get good gas mileage present a more profitable strategy for meeting federally mandated "fleet fuel economy" averages than selling millions of less powerful small cars, which many buyers shun.

General Motors has developed big engines that shut off several cylinders when they're not needed. The V8 in Chevy's SS concept car, for example, produces 420 horsepower when the driver floors the gas, but it renders four cylinders idle when they're not needed. That boosts gas mileage.

In addition, hybrid gas-electric powertrains, such as the one in the Toyota Prius, can also be used to boost either power or fuel economy.

Acura, for example, plans to build a hybrid luxury sedan with 400 horsepower - 150 of it from quiet, powerful electric motors, and 250 from a fuel- efficient V6 gasoline engine.

The electric motors excel at acceleration without consuming large amounts of fuel. But what they fail to do is drive long distances, because motors usually rely on inefficient batteries. That's where the gasoline engine is more effective.

In other words, hybrid cars, too, can be built to favor either power or fuel efficiency depending on the size of the gasoline engine or the battery pack.

Both of these industry tactics demonstrate that it is no longer necessary to sacrifice power for fuel efficiency.

One trade-off in building cars with greater horsepower is higher repair costs. Pumped-up engines work harder than low-powered ones. Components incur greater stress and wear out faster. And many of those components are very expensive to replace.

Despite such costs, says Mr. Cedargren, almost everybody from age 20 to 60 is buying high-powered vehicles.

Auto analysts say one of the top things people look for when test-driving cars remains power.

"Buyers are a lot more willing to pay for more power than they are for [fuel] economy," says Dr. Cole.

Whether they need it or not.

So what do you get when you buy a vehicle with a lot of horsepower? The short answer: A car that zooms.

Horsepower is simply a measure of an engine's ability to work. The more horsepower a car has, the greater its top speed. Today's sports cars with 300 to 400 horsepower can reach speeds edging toward 175 miles per hour - straight-to-jail territory in any state. (Most sports cars contain electronics that limit top speeds to about 150 miles per hour - double the highest speed limit of 75 miles per hour found on Western interstates.)

But don't look just at horsepower if you want a car that accelerates quickly from a stoplight. Instead focus on a vehicle's torque - the force that turns the engine's crankshaft. Like horsepower, torque is on the rise in many new cars. Most of the show cars trotted out recently at the Detroit International Auto Show have similar torque and horsepower numbers.

Engines with high torque often run more quietly than those with high horsepower because they don't have to turn so fast. That relaxed acceleration can be a boon to drivers battling long commutes.

Want an engine with huge torque, decent power, and great fuel economy? Try diesel. Only Volkswagen sells them in the US. Besides the Beetle, Jetta, and Golf, VW may soon offer an SUV with a 300-horsepower diesel engine - with 550 ft.-lbs. of torque. Now that's a people mover.