bop11

Just curious.
If you are driving along using cruise control and go down a hill, you can feel the cruise control try to slow the car down to keep to the set speed. In some small towns in NJ this is good because the local police sit at the bottom of hills with their radar on. I assume the cruise control applies the brakes since I don't see or feel a down shift. If it does apply the brakes does it do it with or without activating the brake lights?
Maybe in the foggy conditions we have around here this week I can find out, but does anyone know. I guess, if it does apply the brakes , the system should let the driver behind know but since you are not really slowing down only 'not speeding up' maybe it doesn't.
As I said just curious.

venchka

I can't find any documentation, but seat of the pants experience says, "Yes. The brakes are applied." Confirmed on a hill near our house with the speed set at 25mph. In third gear you can see the RPMs decrease when the throttle backs off and the car starts to speed up then slows down when the brakes kick in. In second gear the speed is steady because the engine braking is enough. Further confirmed on the highway when I double click from 70 to 60. The brakes definitely slow the car. No clue if the brake lights come on.
Use your rear fog light in reduced visibility regardless.

Wayne

PilotAlan

No idea on brake lights, but in the mountains here I can confirm it IS the brakes. The MB holding speed on some steep 35mph downhills, I had to downshift to 2 to hold speed with engine braking.

It's useful for Europe where they have "average speed" cameras that click you going into and out of a known distance, and ticket you if your average speed is over the limit. Kinda sneaky when there's a downhill in that area. If you set the MB for 50, it will use downshifting and brakes to hold 50.
My wife's Jag has a similar feature, but you have to hit the button (called "Automatic Speed Limiter"). MB does it itself, to maintain your set speed.

dgiturbo

On my 07 ML, the brake lights illuminate if I use the cruise to drop the speed more than 5MPH, or maybe 10MPH? Say from 70 to 60MPH. Visible on dark roadways if you watch the rear view mirror. Neat feature.
My assumption is the same feature would be on the GLK as the systems work the same way.
As for illuminating the brake lights when it is "holding" the cruise speed, I would guess no as there is no dramatic speed reduction from "x" to "y", because the system is just maintaining "x"

bop11

Thanks dgturbo. I knew it used the brakes but was wondering if it indicated to the driver behind you that you were using them. From your post it appears that the brake system has a pressure switch or is electronically connected for the brake light circuit not just a mechanical switch on the brake pedal or pedal linkage.
If you were towing a trailer, slowing down with only the transmission would not be a prudent thing. You would want to activate trailer brakes if the trailer had them.

3.5L

I wasn't aware of this feature in the cruise control. Very cool!

We frequently traverse a long 6% grade. Going up is no problem, but I've been in the habit of manually selecting 5th gear on the way down to keep the speed around 65 without dragging the brakes. Works well, but it appears the CC can do a better job! Thanks! (and even after 11 months of ownership, I'm sure there are still many cool things I have yet to learn about this awesome vehicle).

3.5L (not bored)

BobCrouch

I hate that my GLK cruise control applies the brakes when on a downgrade.. Wastes energy and fuel. Many other cars allow freewheeling on downgrades, and those drivers will be on your tail when your car brakes! Please tell me there is some way to defeat this limiting feature?!!

Koenig1

X2....what he said above . I could care less about possibly 'overspeeding' on a steep downgrade, PITA. The cruise is a little different between kms and mph. In Canada, setting your cruise for ,say, 110 Kms, bump the stick once, and you're at 120 (Yes, I know a light bump will increase 1 km. When I switch to mph for my Florida winter... I really enjoy the 5mph bump.... It seems the 10 km bump seems high... even tough it's only about 6-7 mph hit!
Maybe it's just me!

bop11

The is a stretch of 513 in New Jersey (yes its Pittstown) where the local gens d'armes sit at the bottom of a hill just knowing that you will be going 55 by the time you get to the bottom if you started at 45, the speed limit, at the top. This is one of their local money makers and they do use radar. The cruise control has kept me ticket free for the last few years in this area by keeping the old GLK within ±5 mph of the limit. I have seen several others fall victim on this stretch of road. A little miss-attention here can cost $100, so I appreciate it.
In other areas a slight inward tap on the cruise control turns it off at the top of the hill and a pull resets it at the bottom.

Kevin R

Personally, when I use the cruise control I want the car to maintain a constant speed. There are lots of mountains around where I live, would hate to get a ticket because the cruise control lets the car coast way past the speed limit on a long downhill grade.

Cwdawson

I'm thinking the reasoning behind this is that all speeds in Canada are in 10's (at least I haven't seen an 75 85, 115 or 125 kmh ) for me if I go from an 80 to a 100 zone it's only two taps not four....

rmfnla

Neither was I; it's good to know.

What's not cool, however, is that stupid control on the steering column; I occasionally hit it instead of the turn signal!

MB has used that design since at least the late 1960s; it's time for an upgrade...

balticgreen

They swapped the cruise and turn signal stalks recently, for 2013 I believe. The apparent opposite of you, I thought the old positions were better and I never hit the wrong stalk. Now that they moved them, I always hit the wrong stalk. I guess I'll eventually get used to it.

shotgun_banjo

Only thing I don't like about the benz cruise control is it eats up the brakes and rotors fast when your route is full of hills as it always applies brakes constantly to maintain the speed.

PilotAlan

I like the change, as I drive a different vehicle for a work a lot. If I only drove the Benz, it would be fine. But for people who drive multiple cars, the positioning is problematic.

vin_de_merc

there are pros and cons to this feature. however since it is just a flick forward on the CC stick to turn it off and a quick pull back on the CC stick to turn it on. That is what i did when traveling on I70 through the mountains in Colorado. this way i can take advantage of the hills for fuel savings when there was no traffice going downhill with me and still use CC when i wanted. also at times i just let the GLK CC run the show and slow me down, the best of both worlds. but i do understand boths sides to this question/issue.