Improvements in SUVs and trucks mileage. Worth the effort?

According to a recent article by the Wall Street Journal, the "eco" trend is reaching the bigger boys on the road. Since sales are going down for SUVs and trucks because of high gasoline prices, automakers are trying to improve fuel economy: New clean diesel engines, hybrid powertrains, shredding pounds and all types of "tricks" that help the vehicle use less fuel.

In general terms, the efforts, although significant in relative terms, aren't that spectacular. As an example, let's check the improvements on the Chevy Tahoe. Last year's model managed 15/19 mpg EPA (city/highway). For 2008, the same model has better numbers, 15/21, which offers a 9.5 percent increase in highway mileage, although 21 mpg still isn't great. Nevertheless, the 2008 model has more HP (320 from 295). This is about the same that has happened with the BMW X5, which has increased mileage 2/4 MPG although has increased more the number of ponies under the hood.

Nevertheless, GM has developed hybrid technology for buses, a descendant of which is the hybrid powertrains that will populate the models, namely the aforementioned Tahoe, the Cadillac Escalade, and the Chevy Silverado/GMC Sierra pickups. Is this good? In theory, yes, but this comes at a premium which drivers might or not offset.

Continue reading after the jump a summary of the efforts to increase big vehicles mileage.

How about diesels? Mercedes has installed an oil burner in the ML, hoping that the improvement in fuel efficiency will attract more buyers. Sales of the ML were down a 40 percent last year. Along with the ML, the Jeep Grand Cherokee and the Dodge Durango, models known for their poor gas mileage, are offering diesel options (although at a high premium over gas counterparts). Note that these diesel offerings aren't yet 50-state compliant, which will arrive in 1-2 years time.

Finally, among the "tricks" to improve mileage that some vehicles have added for this year, let's mention a few ones that the Chevy Tahoe hybrid will include: a lighter hood, hatch and driveshaft made of aluminium; lighter and more aerodynamic wheels, thinner seats and even keeping out options such as power-operated rear hatch or power-folding seats. Chevrolet has also removed the roof rack and the two hooks on the front bumper.

The article finishes with a forecast by David Healy, an analyst with Burnham Securities, "Hybrids tend to carry higher price tags, and drivers can't always reap fuel savings without altering their driving techniques" (now tell me if you have never seen an SUV at 85 mph on the left lane) and has a winner: "In the long term, I think diesels have a better shot at winning over consumers".

What's your opinion? Are these efforts worthy? What's the technology that will really help big vehicles to improve mileage?

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