When the 2008 Chevrolet Tahoe Two-Mode Hybrid was named ‘Green Car of the Year’ by Green Car Journal last November, a lot of folks scratched their heads. Sure, the super-sized hybrid boasts relative benefits over comparably sized gas-powered SUVs, but is that enough to regard the Tahoe Hybrid as eco-friendly? The official EPA fuel economy ratings are 21 in the city and 22 on the highway, which represents a 30 percent increase in overall economy, and a 50 percent improvement in city driving.

We had an opportunity to drive the Tahoe Hybrid over the last few days, and to conduct two separate real world mileage loops in order to determine the vehicle’s fuel economy. The first was a highway drive from Cape May, New Jersey to Falls Church, Virginia. The 238-mile stretch ate through a little more than three-eighths of the 24.5 gallon gas tank, and yielded just over 21 miles per gallon, right on par with EPA estimates. Driving style was on the conservative side, as the vehicle stayed in the right hand lane for most of the road trip.

The second drive loop was comprised of mixed suburban driving in and around the Baltimore metropolitan area. Here, we tested the Tahoe hybrid in the type of traffic that 90 percent of Americans experience everyday. The result was surprising. The 151-mile drive test gave us 24.8 miles per gallon, beating GM’s numbers by 15 percent. Again, driving style was very conservative.

The Chevrolet Tahoe Hybrid, powered by its 6-liter V-8 gas engine in conjunction with electric motors, surpassed expectations for efficiency. For those who cannot live without a large vehicle, the Tahoe delivers the promised fuel economy. But the question still lurks: Is that enough to call it a green car, much less the "Green Car of the Year?"