2009 Dodge Durango Hybrid and Chrysler Aspen Hybrid

How would you improve the fuel economy of a large four-wheel-drive SUV without sacrificing a V-8 engine, seating for eight, or the ability to pull 6000 pounds? If you're Chrysler, you add some fancy electric-drive technology and create the 2009 Dodge Durango and Chrysler Aspen Hybrids.

Outside of the familiar 5.7-liter 'Hemi' V-8, the majority of the powertrain - notably the electronically variable transmission - is nearly identical to what's found in the Chevrolet Tahoe and GMC Yukon Hybrids. Stemming from the partnership inked in 2005 between GM and (then) DaimlerChrysler, Chrysler's Two-Mode transmission differs only in its front and rear bolt patterns; the remainder - including most part numbers - is identical to GM's unit.

That gadgetry, however, isn't noticeable at first glance. Park a Durango or Aspen Hybrid next to a Durango or Aspen Limited, and you'll be hard pressed to tell one from the other. The only cues Chrysler gives are three small 'Hybrid' emblems, a stark contrast from the nine logos affixed to GM's full-size hybrid SUVs.

Chrysler has also avoided the "efficient" styling tweaks given to the part-electric Tahoe and Yukon. Hybrid Durango and Aspen models are, aside from powertrain, built identically to non-hybrid models.

That means no aluminum hood, no compact spare tire, and no aerodynamic tricks. Chrysler reps feel certain changes (particularly the spare tire) compromise the truck's ability, and engineers feel other inefficiencies need to be tackled before addressing the DurAspen's drag figures.

Some of those inefficiencies are addressed with the revised Hemi, notably through a revised intake system and a new exhaust-gas-recirculation (EGR) system. Although the Hemi's output drops 11 hp to 345 hp, power produced by the twin electric motors boosts the net figure to 385 hp.

That, of course, is when the truck happens to be running on its second mode. Here, the truck primarily runs on its combustion engine, adding power from the electric motors as a 'boost' when needed (i.e. passing, towing, and hard acceleration), and otherwise using them to recharge the battery pack that lives under the second row of seats.

The bigger gains in fuel economy come during city driving, when the electric motors do the vast majority of the work. Provided the battery has enough charge, the Durango and Aspen Hybrids can drive in electric-only mode up to speeds of approximately 25 mph, until the Hemi kicks in. Even then, the engine often runs in four-cylinder mode, further aiding fuel economy.