Found something out today

[Beanee687]

While driving home from Leeds on the M1, in my C3 Aircross automatic, had the cruise control engaged. Came up against slower traffic in my lane and the outer 2 lanes (4 lane smart mway) had cars passing me so I had to brake this disengages the cruise. The passing cars cleared but the car in front of me lane hogging was only running at 65 mph and wouldn't use the inside lane. I pulled out and passed and my speed went to 74. The road was now going down a hill and I pressed the cruise resume button. To my surprise the box dropped down from 6 to 5th then 4th the revs went up to 4,200 rpm as it tried to slow down to 70 using engine braking. As it slowed it changed back up to 5th then 6th. The rpm at that speed in 6th is about 2,200.
Bit of a fright. If I do it on the level or a slight rise it doesn't do it. I tried it again on a decline and it did again but I paused the cruise and let the speed decay naturally.
Just a heads up for other automatic owners.

[SeaCrosser]

Something watch out for, I guess. Thanks.

[the2ems]

Isn’t that what it’s supposed to do? If you are travelling at 74mph, and you “tell it” to travel at 70mph, it needs to slow down. Mine does.

[Beanee687]

Yes but I did not expect it to change down to do so. Simply shutting the throttle would have allowed it to decay. The changing down and sudden rise in RPM was a bit of a shock.