"Two mode-hybrid": how it works
In a recent interview, one of Cadillac’s top executives implied that all future Cadillacs would be available with hybrid technology. The Escalade will be the first, getting a two-mode hybrid this fall, along with its sisters under the skin, the Tahoe and the Yukon.
But what exactly is a “two-mode hybrid”?
Well, here’s the scoop and here’s why you may be seeing a lot more of this concept from a number of different car companies.
Toyota has grabbed the lion’s share of the publicity about hybrids, but its actually General Motors that has done the most development of hybrids and has the most experience with them. It also has the most advanced hybrid system.
The first practical hybrid system was developed at GM’s Allison Transmission division. It was designed for city buses. The first hybrid buses were put into service in Seattle in 2003.
It is a derivative of that system that GM has been developing for trucks and automobiles. But it hasn’t been alone in that task. When GM decided to migrate the hybrid technology to vehicles smaller than buses, they brought in some partners: DaimlerChrysler and BMW. What they developed will be showing up, in addition to GM’s applications, on the Dodge Durango and Chrysler Aspen in the near future. BMW isn’t tipping off its future product plans, but it didn’t get into this program just for the educational experience. In point of fact, there’s already a deal between the partners: GM will build the hybrid transmissions to the specifications of their partners and the partners will buy them from GM.
So, what exactly is this “two-mode hybrid”?
It is not a “full hybrid,” a term that applies to a vehicle which can run either entirely on electricity, or entirely on gasoline, or combine the two.
It’s better than a full hybrid.
The “two-mode hybrid” has everything that the full hybrid has, but it adds the ability to use the transmission for torque multiplication. By doing that, the size of the electric motors (and, consequently, their weight) can be reduced. GM’s new six-speed automatic transmission was designed to be adaptable to hybrid technology.
It is worth bearing in mind what adapting hybrid technology to city buses has accomplished. A hybrid bus can function with an internal combustion engine half the size of that required in a conventional bus to achieve the same performance, all with significantly reduced emissions and at a noise level so low that it is comparable to that of a passenger car.
Here’s a statistic for you: were the 13,000 buses in the nine largest United States cities replaced with hybrid buses, it would save 40,000,000 gallons of fuel every year.
Now think of applying that technology to Suburbans, Tahoes, and pick-up trucks.
You will be seeing the future of GM.