This is very noticeable in my 2010 as well, feels like it drops an anchor. I don't see how this helps with fuel mileage as you have to get right back in the gas to maintain speed even going down hill. Mine doesn't get any better mileage than my 08 did.

 

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I think I'm qualified to speak on this. I owned a 2009 QC that I traded in for a 2010 CC. I noticed the deceleration difference within 30 seconds of driving off the lot with the 2010.
It is most pronounced when letting off the gas at around town speeds, say, when approaching a stop light. At first I thought the 2010 had different shift points programmed in, but I have since developed a theory related to the 2010's decel fuel cutoff system.
I believe that since the motor is cutting fuel to itself, the tranny is more aggressive with the downshifts.. thereby using the trucks forward momentum to keep the motor spinning with a lack of fuel.
That's my theory..... what's the general opinion of it?
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( I also notice what appears to be more gear noise from the tranny with the 2010, but that may be the different brand of 20" tires between them)

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I'm just curious, did the 09 QC have the same final gear as the 10 CC?

 

Off the top of my head I'm going to say yes because both trucks are running the same rpm at the same ground speed on the same roads. I will have to pull out the '09's paperwork to doublecheck. I also want to say no because the '10 is getting about 1mpg less fuel economy.... But that might be a seasonal issue.

 

I'm not being argumentative here, just asking what might be an obvious question. Are you suggesting that the engine actually cuts off when decelerating due to the decel fuel shutoff system? I have had an engine shutoff on me before at highway speeds and city speeds and, forgetting about the loss of power steering and braking issues, found that the sense of deceleration to be much greater than I've noticed on my Ram when "coasting" to a stoplight. Just throwing the question out there.

 

It's not being argumentative at all, I'm looking for my theory to be debated. I'm not thinking the motor is dead entirely, but being kept alive with engine braking provided by the downshift. If you've ever bump-started a car with a dead battery, all the systems start to function once the clutch is popped and the motor starts spinning due to engagement with the tranny/driveline even though the motor is not technically "running".

 

Wow looks like it was better to grab the first year of a major changeover. They usually say don't buy something first year of big changeover. I have an early 09 build no fuel saver light but I really haven't had anything other than required not out of the ordinary (knock wood). Then again we only have 8000 or so KM's. My wife drives it the most,she is a bit of a lead foot, with the exhaust ya can't fool me when you leave LOL. Even my kid with the Avenger he is like his mom.

 

Not sure I will agree with you, by releasing the accelerator will not compress the engine at high speed, you will notice it more at loor revs. I doubt that it is normal for the truck to slow down as much as you say. I have the 2009 and when I release the gas it just slows down by coasting, if I leave it off eventually I will come to a stop but definatly not withing the next mile,(you get the idea). It is not logisticly correct to make the truck slow down that drastically, you will have someone up in your trunk if he is following close....I would go have a look at the dealer and see what he has to say. Your dif should not be making any noise unless its broke.
The way you are desxcribing your slowing down sounds like it is downshifting. Next time out count the transmission changes, make sure it goes to 5 keep it there for a few minutes and remove your foot off the gas and see what happens, give us some feed back.

 

Well hold on here. I'm not thinking that there's any mechanical problem, just a more agressive downshift at around town speeds. ( 30mph or so ) When letting off the gas in the '09 the truck coasted while slowing, with the '10 there's a downshift that wasn't there before. I think that's what the OP was asking about. I believe it has to do with the fuel cutoff system since that is the only difference between an '09 and a '10... Which is where my enging braking idea comes in.
As far as the gear noise from the front tranny/diff area, I'm wondering if it's cold fluid related. I had the original truck from late July to early January here in the northeast, and never had a chance to compare various noises and quirks between fluids sitting in an 80 degree pan against a 12 degrees. Might just be a personality trait of the truck.
BTW... when asked, my dealer mechanic said the only difference between '09 and '10 "is the badge".