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Message: <blockquote data-quote="GaryM" data-source="post: 31266" data-attributes="member: 9373"><p>That's correct. 8th gear, for some reason, has some pretty strict performance parameters to meet before it will actually shift into 8th gear. But be sure, if you're at 70 mph and the engine RPM are 2200, the transmission is in 7th gear regardless of what the paddle shift on the dash says, even though it says L8. Even with ERS (paddle shift), if the performance criteria is not met, you can't force it. After a lot of testing I figured out that 8th can be achieved with 0% throttle using the paddle shift at 70 mph, on a slight downhill. It will default to 6th, then upshift through 7th then 8th gear slowly. If entering a highway posted for 70 mph you can achieve 8th by keeping speed below 62 mph, 0% throttle. It will stay there as you accelerate to 70 mph if done very slowly. Too much throttle and it will downshift to 7th and stay there. I do it all the time and it works. I get 8th gear (1800 RPM) at least 90% of the time. I know, to some, this all sounds a little goofy and I admit it is. It certainly is not the kind of thing anyone who owns a newer vehicle should have to do the get full use of all the gears and the benefits. All of us accelerate to road speed, level off, and either hold the speed or use cruise control and expect the transmission to shift to the highest gear appropriate for the conditions. In this case, if we drive that way, the appropriate gear in GM's design mind is 7th, even though achieving 8th via the above mentioned methods will work just fine. I live around 25 miles from town, yet when I get it into 8th gear it will stay there and perform very well with fuel economy at around 31 mpg. I've had several conversations with the folks at GM about this without getting one solid explanation as to why the TCM is programmed the way it is in regards to the use of 8th gear. They've agreed that my assessment of how it performs once in 8th is accurate but they are not willing to accept they're mistaken in their coding as to how it must be achieved. They just can't seem to accept that "normal" driving habits will not use 8th gear at all using current programming.</p></blockquote><p></p>

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