Our friend Mike Levine over at PickupTrucks.com spent some time talking to GM’s John Turzewski about the future of the company’s hybrid trucks last week and came away with interesting information. The key to the two-mode hybrid system is two planetary gear sets that allow blending of engine and electric drive over two different speed speed ranges. This is part of what allows the system to get better fuel economy at highway speeds. The other main difference from existing systems is the presence of clutches that allow the gear sets to be locked to four fixed ratios and bypass the electric motors completely for better towing capability.
Mike is now reporting that the next-generation hybrid system could double these offerings to four different drive modes. It’s not entirely clear what that means at this point as GM isn’t saying. However, the upcoming two mode hybrids from Mercedes and BMW are upping the number of fixed ratios to seven and GM could build on this idea. GM has previously said that the next-gen hybrid trucks would up the towing capacity from the current 6,000 pounds to at least 9,000, so more fixed ratios are likely to be part of the mix. The next-gen hybrid should arrive around 2013.