I've just watched LA Autshow Part 2 on SPEED and this is what I've gathered. The Sierra Hybrid will be sold in 6 states. It gains 2mpg over the conventional gas engine (17mpg vs. 15mpg). It's not a full hybrid or even a mild hybrid. I believe it as the ability to shut off the engine when not in motion (several cars in Europe do that) and some... sort of startup assist to reduce the strain on the engine to initially move the vehicle? I suppose that's where the 2mpg comes from since the engine in the Sierra Hybrid is a large 5.7 litre V8. To quote the hosts, "it's almost an insult to the highly respected Prius"
