The Chevrolet Tahoe Hybrid is supposed to improve your city mileage by 40%. If you know the Tahoe, you know how big that thing is. It is a just a bit hypocrite to add electric engines to the existing V8 engine. On the other hand it is better than nothing – American mom’s just love their SUVs.

Chevrolet's two-mode hybrid system developed by BMW adds 400 pounds that the GM engineers had to loose again somewhere else in the Tahoe.
The used aluminum on the rear lift-gate, hood and bumper for instance.
Car blog Jalopnik has a first hand report of the 2008 Chevrolet Tahoe Hybrid.

First showroom Hybrid Tahoe models are expected to be available this fall. See also the Chevy Hybrid page.