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Yes it's true. Diesel locomotives are actually series hybrid electric marvels of motive force and efficiency. I'm sure if I put Goodyears on a freight train you would only drive it only once, however. Ever been stuck in front of the red lights and bells when a train reverses directions? Or stops and starts up again? Like the guy on Monty Python once said, 'It's a simple matter of weight ratios!" 0-60 times of most road going vehicles fall around 10 seconds not 5 minutes.
Also, it's true that the Detroit hybrids use less of their available battery capacity (called State of Charge or SOC in the lingo). My personal (not endorsed by my employer) opinion is it boils down to two factors 1) we have less experience with such vehicles so are more conservative, and 2) the ones who use a large portion of the SOC do so at the cost of battery longevity - and they lie about it. Toyota's official claim was (at least at one time) that they have NEVER had a battery failure in a customer's vehicle. I find it incredible to impossible that any corporation can make a million of anything and not have a single failure.
And trust me, the GM/Chrysler AHS system is a step beyond the 'full hybrid' of the Toyota. The Toyota system relies on a small generator and large drive motor. The AHS system utilizes two medium sized motors and a real transmission architechure to swap their functions for increased high speed efficiency. At low speeds motor A is the generator and B is the drive motor, just like a Prius. Just like a Prius, at some point the output speed becomes too large to efficiently run the drive motor (notice the lower highway mpg rating of the Prius unlike a regular car). At that point the motors swap their function, A becomes the drive motor, and B becomes the generator. Since A has a different gear ratio to the output, the overall motor speeds are lowered (and efficiencies improved). This gives rise to the name 'two mode.'
The downfall of this type of operation is that a portion of the road load power has to go through a complicated path. A portion of engine torque is converted to electricity in the generator motor, sent through the vehicle to transformers, diverted to the battery, electical loads (headlights, DVD players), and the drive motor as needed. The drive motor energy is then converted back into torque. First term thermodynamics teaches the second law, "things go from bad to worse" and none of these conversions is 100% efficient. The more you put in a line, the lower the system efficiency gets.
Fortunately, there's a device already in the car that's about 96% efficient at delivering torque, it's called a conventional automatic transmission (not including the torque converter which this vehicle doesn't have). So, when loads become too high, the transmission reverts to a fixed gear ratio for mechanical efficiency at that operating point. This is where the motors can then behave like the Honda system, and just add torque at the expense of the battery. This is how the hybrid Durango/Aspen can produce 400 hp, while the conventional produces less. It's 'brochure' horsepower, it only happens under certain circumstances, but it does happen, just floor it.
The beauty of this system is that it turns the engine from being a torque and rpm generator into being only a torque generator (and not the only one in the system). Now that you don't need the engine to produce a full range of rpm (typically 1000-6000), an engine that is great at producing torque, but not so great at making high rpm can be used to propel the vehicle. If you're reading this forum, you know what that engine is. What's the difference between an engine that makes 340 lbf-ft (the latest 2.8L VM), and 385 lbf-ft (a Hemi). Not a lot. What's the difference between the fuel consumption of our trucks vs. anything with a Hemi? Significant. This has been brought up, but in my opinion, not absorbed, by the people who count in any automotive company.
The decision making process of the executives (which by now you can assume doesn't inlude me) probably focused on the following...
How can a buyer quickly recoup their investment? Save LOTS of gallons of gas. That's what a move from 14 to 20 mpg does.
Unfortunately, that process relies on the assumption that the guy who bought an SUV last time will buy another. As I point out today at work (to my professional detriment) buyers chose to maximize their dollars per mile instead, they dropped 14 mpg and even 20 mpg SUVs like the bad habit they were. I drive the KJ CRD only because it's the most fuel efficient vehicle that will tow my camper (it's a great bonus that I got it under employee discount). But commuting in it is making less sense every month, so I'm trying to get a 40-50 mpg commuter and keep the 24 mpg truck around for when I need it.
It was interesting to see some of the Hybrid Development Center town halls where the top bigwigs were invited in. During the question and answer periods of both the head of Chrysler and Mercedes product development, the first six questions asked of the executives were not about hybrids, but about diesels. I had to laugh silently and many of my friends asked me why I didn't start the grilling, I just answered, "I didn't have to, the facts speak for themselves!" Our answer was always, "it's too expensive." Sorry about that, I'm not in charge, and they won't let me build a 'sandbox' car, although now I can probably build the team required to pull it off if I needed to.
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2005 CRD Limited Flame Red w/ Renegade rock rails & light bar, AirLift 1000. 225/75R16 MT/R's on cheap black steel wheels, dual MOPAR subwoofers, Ipod kit & seat covers, Samco hoses - totaled and gone. 2008 WK Laredo 3.0L diesel - AirLift 1000, wife won't let me mess with it much. 2013 JK Sahara on order.
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Think about the largest land vehicle you can. The heaviest. The one that moves the most tonnage, all day, every day.
