So I made the dealership put cats on my car and they loaned me a 2011 Silverado LT w/ 5.3 and a 6 sp auto. I hate big trucks but especially hate poor design that is supposed to be innovative. This one has that automatic displacement tech which is USELESS. I drive 180 miles round trip almost all interstate and the truck never went into 4 cyl mode. In town it would if I set the cruise at 45 or so but no other time. I can't figure out why, at a stop light, in normal driving it wouldn't just shift to 4 cyl mode until you hit the accelerator, which is electronically controlled anyway. I never saw better than 16 mpgs in the three tanks I put through it. That's 1 mpg less than our 04 ram hemi quadcab gave us on hwy trips. Also this thing is absolutely gutless.