Usually at highway speeds, when getting back on the gas, a "gentle clunk" is felt more than heard, from somewhere in the drivetrain towards the rear of the car. It's not bad enough to really worry me, but it bothers me enough to write this post! Dealer service dept said, "this is normal". Car has ~6K miles. Opinions?

Tia.

 

 

Sometimes the adaptive transmission computer picks up odd characteristics depending on recent driving inputs. If its doing it 100% of the time after a few days, then something is probably wrong.

 

Might be the giubo or the rubber disc's mounted at each end of the drive shaft?
There was a part number change from 2013 on but your past that. Looks like all V-8's use the same drive shaft to.

Not sure but you have the 6 cylinder instead?
This is the description as they are used on a vast array of cars/trucks for NVH reductions.
Ciubo

Here is the XJ drive shaft and the giubo's are mounted at each end where I circled them in red. Be aware that the middle flex joint is also rubber and a potential source of clunks.



The rear end can also have some slop that will be felt by rolling on and off the gas as you describe. MY prior 2005 S Type R had a very slight amount of this and when the car was in the air on a lift I could rock the differential back and forth a bit.
Never seems to cause any problems and I drove that car until 132K miles.
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Thank you all for the guidance and information.

It's really mild at the moment, I suspect many wouldn't even notice it. The car is under warranty for several more years so will just keep an eye on it for now.