Originally Posted by dannyguo
Me neither, just thought it will shift automatically to highest level when the speed is constant. Glad to know it my previous thought is wrong.
It'll go to the highest gear which will allow enough power to remain at that speed with light throttle input (cruising) for fuel efficiency (especially in ECO mode). It's a little more complicated than that of course but basically if you were in 8th at 35mph you'd have to be giving it serious throttle just to maintain that speed--and lugging the engine. The transmission would then kick down to a lower gear. To prevent this kind of constant hunting for gears, the TCM will not select a high gear like 8th at speeds that low. Just like you won't see 5th, 6th, 7th, or 8th if you are cruising at 15 or 20mph.