Hi, Had a seach on the forum but couldn't find anything on this issue.
I have a 2006 RRSs/c that I have had about a year now. Haven't had much need to use Cruise Control until a recent trip of approx. 1700klms.
Our max.speed limit is 110kph. When set on this speed the actual speed(GPS) varied from between 102 and 118 kph.
Yes it did vary depending on the terain.
I have other vehicles where the cruise control only varies 1 or 2 kph. One has the same ZF auto 6spd.
Is this normal for a RRS or is there somethig wrong with mine
Any feedback would be appreciated as I don't want to get booked for speeding especially when I don't even have my foot on the accelerator.

Can't say I've had the same problem with the ACC on my TDV8. Seems to hold speed pretty stable. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Mine is an SDV6 but it holds speed within a couple of K's but will over speed on a steep downhill run.
Southbound on the M1 (F3) into Sydney near Hawkesbury Bridge for example.
Regards,
Barry 2017 Range Rover Sport TDV6 L494 SE Fuji White
2011 Range Rover Sport SDV6 L320 SE Fuji White Loved but GONE
2010 TRAKKA Motorhome Fiat Ducato GONE (What a dud, don't buy one)
2006 Discovery 3 SE TDV6 Automatic Chawton White/Ebony. Loved but GONE
2006 BMW X5 diesel White/Charcoal, Bought new, Gone after 12 years! Was Excellent.
Ex Member Range Rover Club NSW

Mines pretty useless on downhill '30s' I must admit.

Sorry Fellas if you think I was exaggerating with those speed changes.
I just realized I was.
When the speed kept going up downhill I kept pushing the minus button and of course when it got to level ground it adjusted to the new lower speed.
So it means that it gained about 6-8kph down hill. Still not that good when your trying to keep to the speed limit.
I was speaking to my Auto Trans Specialist and he said its a common problem with the 6spd & 8spd Autos in heavier cars etc. "There isn't enough engine/trans breaking available."
Any comments on that theory

Cracka,
When running downhill (a long downhill) in cruise control mode I flick my auto into sport mode and change down a gear. Provides some engine braking and holds back the speed. M3 (110K speed limit) decent to the Moonee Bridge is another place where cruise control in drive mode runs away. Moonee decent requires dropping 2 ratios to limit speed as its pretty steep.
Regards
Barry 2017 Range Rover Sport TDV6 L494 SE Fuji White
2011 Range Rover Sport SDV6 L320 SE Fuji White Loved but GONE
2010 TRAKKA Motorhome Fiat Ducato GONE (What a dud, don't buy one)
2006 Discovery 3 SE TDV6 Automatic Chawton White/Ebony. Loved but GONE
2006 BMW X5 diesel White/Charcoal, Bought new, Gone after 12 years! Was Excellent.
Ex Member Range Rover Club NSW

CRACKA wrote:

I was speaking to my Auto Trans Specialist and he said its a common problem with the 6spd & 8spd Autos in heavier cars etc. "There isn't enough engine/trans breaking available."
Any comments on that theory

Piffle really.

The transmission does limit the amount of negative torque permitted, but at the end of the day, the car has access to full braking should it need it so it's not really an excuse.  Visiting from DISCO3.CO.UK
2006 Discovery 3 TDV6 Auto HSE Zambezi Silver

Thanks Fellas I'll give the sports mode a try next time, that will at least cut out the overdrive .