Looking To The Future
We've downplayed a few electric hybrid ideas before, but mainly because of the current state of battery production and disposal. We know that there's nothing wrong with wanting to conserve fuel or money; we could use plenty of relief ourselves. But we look askance at those who purchase a hybrid vehicle simply as a status symbol to tout their greenness, when in reality they could be doing more long-term harm to the environment and doing nothing for the short term, as the amount of energy spent to make these vehicles is often more than the energy they save. But looking at hybrid technology in a long-term light, we see what is being done today to make our world, as well as our wheelers, better and greener.
The fact is that Chrysler, BMW, Mercedes-Benz, and GM have developed the Two-Mode hybrid drive system that effectively uses a combo of gasoline engine, electric motors, and batteries to propel modern vehicles with significant fuel savings, both in production and on the road. We recently had the chance to enjoy the Dodge version in the new Durango and Aspen SUVs. These fullsize SUVs are refined and capable and are supposed to be 40 percent more efficient in the city. While these aren't our typical 4x4 of the Year test entrants (and won't be due to the lack of low-range) they showcase what's new now and for the future. The basis for the system is the electrically variable transmission and the fact that the electric motor is inside the tranny. No motors at the wheels, no starter, no alternator, and of course electrically assisted power steering, brakes, and air conditioning. That's because at speeds under 30 mph the engine is usually off and in electric mode.
We did testdrives in the Aspen and the Durango and found it almost unnerving at first. There's no "starting" the engine, you simply push a button and go-quickly and quietly. However, you can actually start the engine if needed, such as if you plan on towing a heavy load, which we also tried. Since it is equipped with the venerable Hemi engine, towing was no more a chore than with any other powerful engine. This Two-Mode is what really impressed us, as did the fact that coupled with the Multiple-displacement System (MDS) variable engine output, we could get economy numbers around 25 mpg while still having the Hemi on tap. An interesting item is that the MDS is enhanced by the torque of the electric motors, helping the Hemi to stay in four-cylinder mode longer, improving efficiency.
However we have to look forward for our off-road needs. There is no low range in these vehicles, so we can't test them in that mode. However the GM version (they all use the same electric/automatic/transmission) does offer low range in the Tahoe, but the electric motivation is disabled in low range. We know Dodge will be using the same Two-Mode system on the upcoming Ram trucks in the '09 or '10 model year, and we hope that we can convince them to have the electric system available in low range. For crawling it could be ideal as all of the torque is available off the line for incredible control, while the gas engine could come on strong in snow, sand, or mud when tire spin is needed. Look for more alternatives in the future, and wait till the aftermarket guys get their hands on this!
The electric continuously variable transmission (ECVT) is unlike anything you've seen. There are no bands or belts like a regular CVT. Instead it combines electric motors (all the colored stuff shown) inside the transmission case, as well as four planetary fixed gear ratios, and has regenerative braking capability to recharge the batteries. The Two-Mode system allows the Hemi or the ECVT to drive the vehicle, or both! We want to hook it to a good transfer case and see what low range would be like-stealthy night runs, anyone?