Little big cars

NEW YORK (CNNMoney.com) -- The most important fuel-saving technology in new cars may be empty space.

Though the average passenger vehicle in America today gets only about 21 miles per gallon - not much different than 25 years ago - it also is much bigger, heavier and faster. We're doing more with that fuel, we're just not going any farther with it.

2007 Nissan Versa

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With gasoline now topping $3 a gallon, it seems car buyers are finally willing to trade in some of that bulk to actually travel farther on their fuel.

But, spoiled as we are by years of driving minivans and SUVs, we aren't willing to give up all that much. Weight and bulk outside are one thing. Space for passengers and cargo is another. We're not going to give that up.

That's why empty space is so important to fuel savings. Buyers will shift to smaller vehicles only as long as they can still stretch their legs and carry some wood sheeting once in a while.

Some of the basic techniques for opening up small cars have been around for decades. Front wheel drive - now the de facto standard for passenger cars - became popular mostly because it opens up interior space. With the engine, transmission and such all stacked up over the front wheels, the rest is left as little more than a big people-hauling trailer.

But auto makers have been working on a few other tricks to get the most space out of a tiny box.

Nissan's new Versa is, perhaps, the best example. Outside, it's a teeny car. At least it is by U.S. standards. In Japan and Europe, it's on the big side of its class. But sit inside and you'll think you're in a midsize car. By the numbers, front and rear seat legroom nearly equal that of a Toyota Camry.

Everything in the Versa is about fitting "big" into a little package. The Versa is short, front to back, but it's tall. The seats are mounted high in the car's body so that, when you get into the car, you aren't falling down into your seat. Even the engine and rear suspension were specially engineered to intrude into as little of the car's precious space as possible.

The Versa's ride and steering were also tweaked for that "big car" feel, not something that all small car buyers will appreciate. Still, the overall impression of size is remarkable.

Other cars now on the market exhibit similar genius in stretching the carrying capacity of a relatively small space. Check out our photo gallery for a few more examples of spacey thinking in cars.

Gallery: Spacey cars

Fuel-saving know-how here...car buyers just have buy

Consumer Reports: Fuel economy most important to car buyers

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