In large-SUV history, this just might be the single greatest leap forward in powertrain technology. So why does GM want to put such an impressive piece of technology in such an unpopular vehicle? The answer, says GM group V.P. of powertrains Tom Stephens, is simple: "This choice highlights our commitment to save as much fuel as possible by applying our best technology to the highest fuel-consuming vehicles first."Whether GM's become a better corporate citizen remains to be seen, but given this is a fuel-gulping 5600-pound sled, the results are impressive. Recently released EPA fuel-economy numbers don't look stellar at 21-mpg city/22-mpg highway, but that's a huge jump up from a non-hybrid. Our comparably equipped long-term 5.3-liter V-8 GMC Yukon averaged 13.9 mpg combined (around 12 mpg city/ 18 highway). The same city routes in our Yukon 2-Mode Hybrid yielded 17.7 mpg with a combined average of 18.2 mpg over three tankfuls. In a world where O.E. designers and engineers are slashing and clawing for a fraction of a percentage point to improve fuel economy, a year-to-year jump over 30 percent (combined) is impressive.
The Gen IV all-aluminum 6.0-liter V-8 and four fixed gears (slotted through the two electric motors) makes this the most powerful hybrid sold in the U.S.
Subtle differences between hybrid (left) and non-hybrid (right) Yukons. Note absence of foglights and flush bumpers.
Interior parts and pieces are identical to stock Yukon's, but do offer an "Economy" gauge and weight-saving seats.
GM included two separate readout strategies to provide the driver with instantaneous information: one analog gauge, one computer screen. The economy gauge teaches the driver (swinging needle) how to use the most efficient braking and accelerating techniques (in a nutshell, extreme smoothness rules the day). Similarly, a dedicated "Hybrid" readout on the nav screen identifies where the power is coming from (battery or engine) and where it's going (wheels or battery). Both are simple and easy to use.
Also included to this SUV models are a host of exterior changes designed to improve aerodynamics. Gone are the foglamp and tow-hook openings. The grille is slightly larger for better cooling. The roof rack rails are eliminated for less drag. Runningboards are tapered front and rear to decrease wind resistance. The previous round body shape was given sharper cuts to hold air, more shapely rear taillights cut through wind better, and a longer and wider front air dam moves more air underneath.
resource: www.motortrend.com
