Munday Chevrolet

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 C_D. 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 C_D 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 "C_D" 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 C_D 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 of 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 C_D rating of 0.360 and features EPA-estimated fuel economy of 21 mpg city and 22 mpg highway.