• Jun 11th 2010 at 2:02PM
  • 22
It's not all that often that SUvs pop up on this site and even less often that one weighing in at nearly three tons graces our pages. Truth is, we rarely have reason to write about these gargantuans. Why? The answer is simple, they aren't usually what we would call green (yes, yes, we know the whole gallons per mile thing). Every once in awhile we feel bad for overlooking some of the green advancements that many SUVs have made in recent years and self-pity drives us to write up something about these behemoths and call it a day. That time has come again.

Chevy has made a few aero enhancements to the Tahoe that decreases its coefficient of drag to a best-in-class 0.379. According to General Motors, the next closest competitor to the Tahoe only manages a Cd of 0.404 and the average for all of the Tahoe's competitors comes in at 0.416. With best-in-class drag numbers, Chevy has managed to improve efficiency from the 2009 Tahoe ratings of 14 miles per gallon city and 19 mpg highway up to the 2010/11 numbers of 15 mpg city and 21 mpg highway. The improvement may sound minor, but every little bit helps. If you're in the market for a big SUV and want to get more miles per gallon, the Chevy Tahoe Hybrid offers 21 mpg city and 22 mpg highway with an even-lower-yet Cd of 0.360. By tweaking the exterior of the Tahoe and dropping the draggy appearance, General Motors has shown that a mere cosmetic makeover can make a difference in fuel economy. Follow the jump for more info on the aerodynamic benefits of the 2010/11 Chevy Tahoe.

[Source: General Motors}


Want more miles to a gallon of fuel? One way to go farther is through efficient vehicle design and a low coefficient of drag or CD. When it comes to full-size SUVs that slip most easily through the air, look no further than the Chevrolet Tahoe.

The aerodynamic design of the 2010 and 2011 Tahoe results in a segment-leading CD of 0.379. The next closest vehicle in the segment has a rating of 0.404 and the average for all competitors is 0.416.

"For owners, the Tahoe's aerodynamic advantage means fewer fill-ups, and more miles per gallon," said Greg Fadler, GM aerodynamics engineering group manager. "We estimate the Tahoe delivers over an extra mile per gallon at highway speeds as compared to the average coefficient of drag for full-size SUVs."

A vehicle's drag coefficient or "CD" is a rating of the vehicle's aerodynamic shape efficiency. The lower the number the less resistance the vehicle shape has to the air. Key design features helping the Chevrolet Tahoe slip through the air include a shaped airdam, one-piece front fascia and low drag outside side-view mirrors.

"We constantly provide data to our exterior designers that shows what changes in design have on aerodynamic forces," said Fadler. "It comes down to fine-tuning shapes for every possible thousandth gain in CD while still allowing for compelling overall design."

At highway speeds aerodynamics have the largest impact on fuel consumption. Aerodynamic drag accounts for approximately 30 to 40 percent of mechanical work energy an SUV on the highway, directly impacting vehicle fuel efficiency.

The importance of low-resistance design is illustrated by the fact that it takes 20 percent more fuel to overcome aerodynamic drag at 70 mph than 60 mph.

The 2010 Tahoe, which seats up to nine, offers EPA-estimated city/highway mpg of 15/21 (2WD and 4WD models). The Chevrolet Tahoe Hybrid has an even better CD rating of 0.360 and features EPA-estimated fuel economy of 21 mpg city and 22 mpg highway.

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    • 1 Second Ago
      • 8 Months Ago
      It's still a pig
        • 8 Months Ago
        They should round off all the corners and call it the chevy boob.
        • 8 Months Ago
        ... with a lipstick.
      • 8 Months Ago
      and it seems Audi's Q7 claims a Cd of 0.34-0.37
        • 8 Months Ago
        @Nept.... i mean, Middle Way?,

        I'm stoked that both companies are making an effort. If Ford can jump ahead in one area, then GM will work even harder to pass them, and vise versa. Competition for higher mpg's is fantastic in my book. May the best car win... until someone else makes one that's even better!
        • 8 Months Ago
        Middle Way:
        You've got to be kidding me. Have you ever looked at the mpg figures on Ford trucks? They've always been awful and they are still bad. GM has been way ahead of them all along and continues to pull away.

        For example, the Tahoe now gets the same mpg as a 2WD Ford Explorer, despite being much much larger.

        Ford hasn't really released their big bombs in the truck market yet though, so perhaps they stand a chance of catching up to GM.
        • 8 Months Ago
        I know you know the meaning of Cd, and wasn't trying to insult your intelligence or anything, just an observation.

        I don't think it's the weight that puts the Q7 in the lower class, I think it's cargo volume, wheelbase, towing capacity, etc.

        "Need" vs "want" is very interesting in the case for a vehicle. A family of six arguably needs a vehicle designed for six or more people. If that family enjoys doing anything other than showing up at their destination, they need cargo room for the stuff they bring along with them. If that family is fortunate enough to have a boat or anything that needs trailering, then they'll need a vehicle designed to tow whatever they have. So while they might not "need" a Tahoe, or a boat, or even a fourth child, they do have the right to one if they "want" one [and can afford it]. Of course, if they don't need a Tahoe, then what do they need? Should they do without the boat? Maybe they should ride in six tiny cars, or ride their bikes, or walk where they are going. None of those things are totally outside the realm of possibility, people were walking everywhere they went for the first couple thousand years. What makes us unable to walk? Where do you draw the line?

        Dan Frederiksen may not need a Tahoe, but the soccer moms might, the boaters might, the hunters might, the CIA seems to make good use of them, and plenty of workers ride in them every day. On the rare occasion, there is even a legitimate excuse for owning a H2 Hummer... but I won't try and make that case for them, it's nothing more than the previous generation Tahoe with a lift kit and a different body. It's a free country, advocate what you believe in, but people are free to choose what they think is right for them.
        • 8 Months Ago
        I agree with Matt. But they've got their work cut out for them. Ford is steamrolling the improvements across their entire lineup. There are legitmate uses for these vehicles and people don't often buy these ones for show anyway.

        "The importance of low-resistance design is illustrated by the fact that it takes 20 percent more fuel to overcome aerodynamic drag at 70 mph than 60 mph."

        Really? maybe in a SUV, but all my compact cars drop maybe 1mpg tops at those speeds, lol..
        • 8 Months Ago
        Q7 is nowhere near the same size, though, so it's probably in a different class. CdA is more important, but Cd does give some indication of how efficient the shape is, regardless of size... sortof a bang for the size-buck, if you will. Who really needs a Tahoe sized SUV? Some people do, and I'm glad that GM is making an effort to raise the bar on the low end too.
        • 8 Months Ago
        noone needs a tahoe. it's an expression of thoughtlessness. a cultural sickness. same as obesity.
        and I know what Cd means

        the Q7 weighs a bit less than the Tahoe but not much.
        • 8 Months Ago
        ( yeah, i am neptronix )

        I wish that were the case. GM is always a step behind. I'd love to root for them... but they continually fail to impress. Hopefully the Volt will be the exception to the rule.
      • 8 Months Ago
      The real question is:

      If the Tahoe Hybrid has a drag coefficient of 0.360 compared to 0.379 for the non-hybrid version with presumably a small amount of changes - why aren't all Tahoes outfitted with the same aero-package or at least made available as an option?
        • 8 Months Ago
        Some people like huge panel gaps!! ;)

        Chevy also is really... really guilty of catering to people who don't give a crap about fuel economy and will buy their car based on a $500-$1000 difference.
        • 8 Months Ago
        Wouldn't be surprised if the hybrid were lowered to increase mpgs at the expense of off road capability
        • 8 Months Ago
        Porsche is also really... really guilty of catering to people who don't give a crap about wasting thousands of dollars for trivial little optional features like a few extra pieces of leather wrapped around a few knobs.
        • 8 Months Ago
        The Tahoe should be measured by a different coefficient.....

        coefficient of stupidity......
        • 8 Months Ago
        That's a very good question. My guess is that money is involved in the answer, but I'd love to see a response from the company about that.
      • 8 Months Ago
      Tahoe could do a lot more to reduce fuel consumption.

      Put a beefier version of the Volt powertrain in a Tahoe and you can have excellent fuel economy and 20 miles all electric range or more. It's a no brainer.

      GM, why do you have no brains?
      • 8 Months Ago
      if one wants to greenwash one's ignorance rather that think a little.

      and Cd is just part of the aerodrag story. the cross section area counts too so the interesting value is CdA

      and of course it's heinous weight matters greatly in the fuel economy.
      so.... not so green really : )
      • 8 Months Ago
      15 MPG City???? Wow!!!!!!

      Looks like we're on the fast track to foreign oil independence.

        • 8 Months Ago
        "support my own"
        Sorry, I do NOT support the UAW.
        I do NOT support the failed Detroit mis management.
        I do NOT support Obama's pet car company.

        But, I have been forced to support this failed company via welfare.
        • 8 Months Ago
        Many of U really come off as CLUELESS. It's actually sad that so few of U even remotely try and gain an iota of knowledge about these vehicles U post about.

        Compare the Tahoe vs the Land Cruiser, Sequoia, Armada, and Expedition and U will instantly feel like complete idiots concerning who's who in Fuel Efficiency in the SUV market. Hell the Tahoe actually gets better fuel economy than the Ford EXPLORER... and damn BEATS the Honda Pilot... a vehicle with 70 less HP, cant tow for jack, and is about as sissy as a Barney the purple dinosaur.

        Support your own... and stop hating yourself.
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