IS 300F Sport cruise control

[Mikeyb999]

My CT will hold the speed downhill using the regen braking to a point, but on steep hills it cant and the speed will creep up.

Don't think I've drive a car with normal cruise that will hold the correct speed down hill.

[Rabbers]

I recently had occasion to test the ACC's ability to maintain set speeds of 100kmh and 120kmh, as per the indicated limits, on steep downhill

stretches of motorway of as much as 15km in length (e.g. the descents on either side of the Gotthard Tunnel in Switzerland, and even steeper

albeit individually shorter ones around Kassel in central Germany where the main deterrent to speeding, apart from good sense, is the presence

of worryingly short sand-filled escape lanes for use in the event of brake failure).  When there were any deviations at all from the settings, they

were no more than +1-2kmh on the steepest and straightest bits, which was certainly not enough to warrant downwards re-adjustment with

the control lever.  Occasionally, the speeds reverted to their settings as the result of the slight slowing effect of curves or changes of lane.  The

deviations were no different from those I have also observed in the non-adaptive cruise controls of all IS generations back to the 200.

[bestcover]

21 hours ago, NemesisUK said:

From approx 25mph for me also.

From the handbook ... 

Do not use cruise control in any of the following situations.
Doing so may result in loss of control and could cause an accident resulting in death or
serious injury.
● In heavy traffic
●On roads with sharp bends
● On winding roads
● On slippery roads, such as those covered with rain, ice or snow
●On steep hills
Vehicle speed may exceed the set speed when driving down a steep hill.
● During emergency towing

I wonder what constitutes a steep hill?

Thanks for your input

 

[bestcover]

2 hours ago, Rabbers said:

I recently had occasion to test the ACC's ability to maintain set speeds of 100kmh and 120kmh, as per the indicated limits, on steep downhill

stretches of motorway of as much as 15km in length (e.g. the descents on either side of the Gotthard Tunnel in Switzerland, and even steeper

albeit individually shorter ones around Kassel in central Germany where the main deterrent to speeding, apart from good sense, is the presence

of worryingly short sand-filled escape lanes for use in the event of brake failure).  When there were any deviations at all from the settings, they

were no more than +1-2kmh on the steepest and straightest bits, which was certainly not enough to warrant downwards re-adjustment with

the control lever.  Occasionally, the speeds reverted to their settings as the result of the slight slowing effect of curves or changes of lane.  The

deviations were no different from those I have also observed in the non-adaptive cruise controls of all IS generations back to the 200.

.....and to think I only want 30mph on the A27......

[200h]

use the paddles and knock it down a ratio or 2 it will hold your speed better than using cruise control,

it will also recharge your batteries at the same time.

[rayaans]

My sons mk5 Golf will hold speed with only a 2mph deviation on the m62 eastbound towards Huddersfield. You can feel the car braking. Same on some recent BMWs I've tried. Not had an issue with the IS or RX cruise control either, deviates a little more but not drastically.

[NemesisUK]

Is it braking (are the brake lamps coming on?) or engine braking?

My CLS55 was very good at keeping the speed down, even without using the radar cruise. My C class not so good.

The RC will gain speed very quickly, no engine braking to speak of at all but then that's good for using regen braking.

[olliesgrandad]

Every car I've owned with cruise control apart from a mini with camera controlled adaptive cruise control has gathered speed on a descent. The mini however on several occasions misread the surroundings and emergency braked on a clear motorway causing consternation to those following me. 

 

[Rabbers]

18 hours ago, NemesisUK said:

.....point #1 is quite interesting, wonder under what circumstances that might happen?.....Cruise control is automatically canceled in any of the following situations....● Actual vehicle speed falls more than approximately 16 km/h (10 mph) below the set speed.....

I have always wondered about that myself, and can only imagine it could happen in the event of an unusually high full-frontal headwind.  The only

occasion when I actually expect the car to slow significantly because of a headwind is upon entering high viaducts/bridges with the wind-sock

pointing directly at you. Since my own automatic reaction is then always to disengage cruise control and drop down a gear or two in order to keep 

the car steadier, I really cannot say if the system would do so of its own accord, though, as the manual states, I strongly suspect it might.

9 hours ago, NemesisUK said:

.....Is it braking (are the brake lamps coming on?) or engine braking?....

I personally find it difficult to tell at medium-to-low speeds unless I am in Sport or Sport+ and thus observe the revs needle.

 

[paulrnx]

It doesn't maintain the speed set down a steep hill. It just doesn't. Not designed and set up to do this. If people are maintaining the same speed downhill then it is the regenerative braking (in a hybrid) that is reducing any speed increase as a result of the hill or binding brakes or some other gremlin. It's not the cruise control. On an IS.

[rayaans]

On 02/08/2017 at 11:37 PM, NemesisUK said:

Is it braking (are the brake lamps coming on?) or engine braking?

My CLS55 was very good at keeping the speed down, even without using the radar cruise. My C class not so good.

The RC will gain speed very quickly, no engine braking to speak of at all but then that's good for using regen braking.

Yes the brake lights on the Golf and recent BMWs since 2012 come on. I believe bmw market their cruise control as "with brake function"

[bagpus]

On 02/08/2017 at 1:06 PM, Ian J. Parsley said:

I'm actually a little surprised there are any cars with "regular cruise" which do *not* increase speed when going down a hill. Regular cruise control only affects the "accelerator" (at least in its original form), so it is inevitable that on steep hills speed will increase if you do not hit the brake.

On my IS300h Lux, certainly speed increased on hills; notably one which was a 30 zone going sharply downhill (even with cruise on this went up to 40); and another a steep motorway incline where 70 soon became 80. It is actually helpful to turn the system off.

It may be possible that some new models have regular cruise which also affects the brake. The adaptive cruise control I now have in the NX does (so, on the aforementioned slopes, speed is more or less maintained).

(See a post I put up about a week ago on what cruise actually is.)

Sorry, had 2 BMW's before my Lexus both had standard cruise but they also had "brake function". This would brake the car if it started to speed when going down hill thus maintaining the set speed.

The only advantage I would add over the lovely IS......I hasten to add!!!

 

[NemesisUK]

1 minute ago, bagpus said:

Sorry, had 2 BMW's before my Lexus both had standard cruise but they also had "brake function". This would brake the car if it started to speed when going down hill thus maintaining the set speed.

The brake lamps illuminated?

[bagpus]

1 minute ago, NemesisUK said:

The brake lamps illuminated?

Yes they did you could see them in the rear mirror..... Also, if you reduced cruise from say 50 to 30 mph, you could feel it brake rather than coast back down to speed. Not a bad function to be honest.

[rayaans]

42 minutes ago, NemesisUK said:

The brake lamps illuminated?

Yes it does.

I tried it on my sons mk5 golf and that maintains speed down a steep hill. It doesn't get faster but also doesn't put brake lights on.