I wa doing about 75 mph and saw the RPMs were around 2000. No wonder gas mileage is good for those that travel mostly at highway speeds. My question is: At 75 mph I wanted to see how quickly it would get up to ~ 100 and what the RPMs would do and if I could finally hear the VTEC kick on. RPMS quickly rosed to about 3500 at about 90 mph and I saw some traffic back up ahead so I let off the accellerator and the RPMs quickly dropped back a bit over 2000 but I was still doing about 85 MPH. Almost like it went into another overdrive gear. What was that all about? Why while accelerating did the truck stay in what seemed to be a lower gear than Overdrive and when I backed off the pedal the RPMs lowered noticeably and Overdrive seemed to be re-acquired? This is my first fly by wire gas pedal and noticeably the most advanced, computer controlled transmission I have owned so these factors are probably affecting my perception of how gearing feels to me.

Your truck probably shifted down with your sudden acceleration. Which is why you saw the higher RPMs. When you released the accelator the truck accepts that speed as your new cruising speed and shifted back to OD.

If you want to feel the gear change put the RL on Cruise Control at 75. Once you hit a clear stretch of road use the steering wheel accelerator button, just hold it down for a few seconds. The RL should downshift and accelerate.

The sudden drop in RPM when you lifted was probably a combination of the transmission upshifting to fifth and the torque converter unllocking. As long as Grade Logic hadn't kicked in, you were just coasting.

I was on a flat road so grade logic should not have been involved, and I was under power and not truly "coasting", but the torque locking is an intrigueing concept and I would be interested in learning more about how this may have affected my experience. Both of you have good explanations and thanks. I don't think I will be able to drive that fast on a regular basis around where I live; just too much traffic to slow me down.

Most modern transmissions have the ability to "lock" the torque converter. What that means is that when running under low load conditions, the two halves of the torque converter locked together so that there is no converter slippage. It is essentially the same effect as you would have with a manual transmission and clutch and helps increase fuel mileage. When the load increases the converter "unlocks" and torque multiplication occurs. When you back off on the gas, the converter always unlocks (on transmissions without Grade Logic), allowing the engine RPM to drop and the vehicle to coast. With Grade Logic engaged, the torque converter does not unlock and thus provides engine braking just like a manual transmission. Grade Logic goes beyond what a manual transmission will do in that it will downshift by itself to maintain the speed you have set.
For a more detailed explanation of torque converters work, try HowStuffWorks (http://auto.howstuffworks.com/torque-converter.htm).

For a more detailed explanation of torque converters work, try HowStuffWorks (http://auto.howstuffworks.com/torque-converter.htm).
HowStuffWorks is a great web site that I visit only occasionally. Thanks for the link, Webwader. It was an interesting read. :)

Thanks. Good stuff. A little extra knowledge to a fool is good in my book.