dang might have to wait.....hmmmmm

 

The overdrive on the 6 speed is .68; the OD on the 4 speed .70

Is that really that big of a difference?

With my LQ9 I NEVER have to downshift on the highway, and that's with 3.42s. Actually, the computer refuses to downshift because it doesn't sense any stress on the engine. I can't imagine that the L92, with almost 40 ft/lbs more than a 6.0 needs to downshift on the highway.

 

hopefully this will give u also a better awnser on ur question http://www.youtube.com/watch?v=TZupbloIxUw

 

I've driven a 6.2L Denali XL back and forth to Jackson Hole, Wyoming now many times. It's 900 miles one way and I say it's geared high and doesn't have much torque in overdrive. It has to downshift for even slight accelleration and any kind of grade, I know because I've experienced it first, hand not because I've looked at some numbers on a web page. This my experience with them. I tried to keep it simple and relevant but since there seems to be some scepticism, I would suggest you find the thread that talks about the 6L80-E specifically. I've also not included my observations on the shift programming problems when cruise control is engaged. The difference in driving one of these trucks isn't coming from the variable valve timing or the increased power, or even the axle gearing, it's the transmission. Many of us have driven a truck with a 700R4 or the crappy electronic version of it for over a decade. Everyone's used to four speeds. The 6L80-E does not work anything like a four speed. It changes gears constantly - a behavior in a 4-speed that would make you think it's malfunctioning. It also doesn't have overrun, so when you lift your foot the PCM hold engine speed high enough with electronic throttle to wait for the transmission to upshift, otherwise you'd feel a lunge every time you lifted your foot in a low gear. They drive DIFFERENTLY, that is my point.

 

I'm definitely not trying to argue with you James. Not at all. It almost seems like you're saying that the 6.2 is kind of anemic on the highway which seems odd given the engine's power. But then again, like you said, the 6 speed is completely different in it's operation.

 

Its actually 0.667 6th gear.

And with a 4.02 first gear the 3.42's are more like 3.73's.

 

I've had mine since January and so far I love it. The 6L80 does take some getting used to though. At first the constant shifting bothered me but I don't notice it now. The tranny also feels a lot different when it shifts. Its hard to explain but it feels more like a smooth manual shift more so than a typical automatic shift. The tranny does have some faults though. At times it feels like it has a mind of its own. Especially when it comes to down shifting at a light. Sometimes it feels like it gets confused then frustrated and slams you into the next gear. GM does have a TSB for this that helps but doesn't completely eliminate it. To tell you the truth I barely notice it now since happens so rare.

Mileage. Well this isn't a civic. It does get decent mileage all thing considered. I average 16-17 mpg per tank. Thats probably close 80% highway mileage. It gets real thirsty when your stuck in the city. I have seen as high as 19 mpg on a road trip from Minneapolis to Joliet, Ill. Not bad considering its a 6000lb 400 hp AWD brick going down the road.