About a year from now, General Motors will face a very interesting conundrum. The company will already be producing a version of its full-size pick-up trucks with a Two-Mode hybrid system. For the 2010 model year, another new engine will be added, a 4.5L diesel V8 that meets Tier 2 Bin 5 emissions requirements in all 50 states. The hybrid system gives a 30 percent boost in fuel efficiency over a 5.3L V8. The diesel should also offer a similar boost. The hybrid is a very expensive system to build. The diesel may be less expensive. The hybrid system works well in warm weather but not nearly as well in cold temperatures. The diesel should do much better in cold climates. The diesel should also provide better payload and towing capacity. It will be very interesting to watch how GM markets these powertrain options and how the fuel efficiency compares in the real world between the diesel and hybrid drivetrains. In the meantime there is a good video from the GMNext website with Charlie Freese, executive director of diesel engineering at GM, in which he describes the design of the new 4.5L Duramax. You can check out the video after the jump.