Fuel for thought

Mazda invited us to a recent, local media event to show off their 2008 CX-9 SUV. For the new model year, this three-row crossover vehicle sees its engine enlarged from 3.5 to 3.7 liters. The result is a 10-hp increase to 273, and a 21 lbs.-ft. boost in torque to 270. Company officials were quick to point out that the bump in power comes with fuel economy equal to last year's model. When Honda came to our track to show us their new Accord in June, the song was the same: More ponies without consuming more oats.

While this news is all well and good, and our hats are off to the engineers who can make engines more powerful without sacrificing fuel economy, one has to wonder what those same engineers could do if they set out to improve fuel economy without bothering to increase power. After all, does the world really need a 300-hp Accord? (Honda is getting close; the current top rating for an Accord engine is 268 hp.)

A 269-hp Toyota RAV4 V6 that can accelerate from 0-60 mph in 6.7 seconds can certainly deliver the kids to school at anti-social speeds, but it's unlikely that's why most people buy small SUVs. The V6 nearly matches the four-cylinder's fuel economy--an impressive feat--but would most V6 buyers give up a second or two of acceleration for a little less quality time and cash spent at the pump?

Press coverage of the recent Frankfurt Auto show indicates manufacturers showed European car shoppers a wide assortment of new models and concepts that put an emphasis on going green rather than going fast. But while the diesel hybrid shown by Citroen--reportedly good for 90 mpg--is impressive, it's highly unlikely to ever see U.S. shores. Just as well, a host of other carmakers showed a variety of plug-ins, electrics, fuel-cell vehicles, and brand-new technologies that could influence home-market products. Mercedes-Benz, for example, unveiled a full-sized sedan concept powered by a twin-turbocharged engine displacing just 1.8-liters. Packed with high-tech features, the small engine is said to deliver 0-60 mph times of about 7.5 seconds in the big F700 concept sedan (pictured), while also returning 44 mpg.

Manufacturers today are responding to consumer demand for performance, and it will take a shift in domestic market priorities before car engineers are driven to focus on economy over performance. Hopefully, it won't take European fuel prices before some of these innovative powertrain alternatives gain traction in the United States. Given the capabilities of today's vehicles, it's clear we can go green and still get the kids to school before the bell rings. And maybe even put a few more bucks in the college fund while we're at it.

--Jim Travers

Comments

[Sue F]

I also think if a car manufacturer out there made an AWD vehicle with 30+ mpg, the world would beat a path to their (sales) door. I know I would, and I'd arrive with many outdoorsy friends.

[Paul R]

This makes me wonder about the limitations of gas-powered engines. I'm no engineer, but it seems as if the size and power output of a gas engine matters less than the engine's technology and the size of the car it propels (weight and drag), as far as fuel economy is concerned. In other words, have we maxed out the efficiency of gas-powered engines?

Does reducing the size and power output of an engine using the same level of technology really cause a nominal increase in fuel economy? I don't think so given the evidence of only slight MPG differences between 4 and 6cyl Accords and RAV4s. Keep in mind the MPG differences are partly due to the heavier weight of the V6s.

I believe manufacturers must focus more on non-gas engine technologies (e.g. diesels, hybrids) or design cars with lower weight and less drag to significantly improve fuel economy.

[David]

" In other words, have we maxed out the efficiency of gas-powered engines?"

Back in the 1980's, Toyota experimented with ceramic engines. These engines can burn at extremely high temperature without the need for a cooling system. The benefits would be an extremely efficient engine with much lighter weight providing high power and high mileage. Today, manufacturing technology isn't there yet. Who knows about the future.