Difference between 09 and 11 Hybrid fuel economy

[lt1gmc]

Everyone pretty much knows the highway mileage rating on the 11 Hybrid is 23 versus the 20 on the 09. I have an 09 and just yesterday test drove an 11 Denali Hybrid. Noticed a couple of things, but the first is the 11 went into V4 mode a lot more on the highway than my 09. Noticeably more time in V4 mode at speeds of 60-75 mph. Also noticed the Denali had an operating back window instead of fixed, had a steel hood, bumper hitch cover, cooled seats, and I believe a heated steering wheel. Nice ride, and over its 87,800 miles had used 4550 gallons of gas, a nice 19.29 mpg average overall. Not bad.

 

[Rockytfox]

Price?

 

[lt1gmc]

32k

 

[jprevost]

I'd also like to know the differences in MPG being so different. I should know if the feds changed the testing between years but I don't. Being lazy I'm hoping somebody else would report why there is such a big difference between years. 3mpg is too much. The engine codes changed from LFA to LZ1 but I can't for the life of me believe the wikipedia notes about the differences.
The engines are near identical except maybe the different valve cover PCV shield and oil pump divert deflector? I'm going to edit that wiki page. It makes the 09 look inferior by the wording.

 

[lt1gmc]

Any others have actual highway mileage numbers for the 2010 and up Hybrids? Thinking about getting a newer or low mileage one to replace my 160k mile one.

 

[dszx13]

I have a 09 sierra. It's a slammed 4wd and I'm getting 21-23 mpg city and Highway miles

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