cyberorth

Have we figured out if we can turn off the braking function of cruise control?
This is not a distronic question.

peet

Braking function???

lomita

Dunno about your C63, when I let off the throttle the car begins decelerating immediatley, no matter the gear, or turning off the cruise control!

cyberorth

When your speed is above what you set on your cruise control, the MB brakes kick in automatically to take the speed down to cruise control setting. Other (lesser) cars just coast to that setting.

I want to be able to coast - not brake.

lomita

You get to have your cake and eat it too, except on steeper downhill gradients.

This is right out of the book:

"On downhill grades, the cruise control
maintains the set speed by braking with the
vehicle’s brake system.
Vehicles with automatic transmission:
In addition, on longer downhill grades the
automatic transmission will downshift
automatically."

I do want to mention one of my initial observations, the C63 AMG is not a good coaster. With its 11.3:1 compression ratio engine, it decelerates immediately as soon as one takes their foot off the throttle. I love how this car prowls around. You can come damn near to a full complete stop without touching the brakes. On the other hand, you can stomp a full pedal of brakes and the car doesn't even throw you out of the seat or spill your soda, stops on a dime. The problem are the cars behind you, they can't stop as fast, so you better be eying your rear view mirror in that case and braking accordingly. None of my other cars seem to decelerate this way. They didn't have 7 speed tiptronic transmissions nor hand built high compression engines.

On roads without gradient, the cruise control is able to achieve onspeed condition from an overspeed condition by closing the throttle, the vehicle decelerates by engine braking, coasting back to the set speed.

On steep downhill gradients, the acceleration of the vehicle due to gravity coasts the vehicle beyond the cruise control set speed, even overcoming the engine braking obtained with closed throttle. When this is the case, the vehicle brakes are applied by the cruise control. You get engine braking and vehicle braking by the cruise control to achieve onspeed condition from overspeed condition. Pretty slick.

And lastly, the transmission even downshifts to prevent an overspeed condition with the cruise control selected when going down grapevines. That means three means of speed control are serving to maintain an onspeed condition: engine braking, vehicle braking, and tranny downshifting. What a great system.

In an overspeed condition, with your foot on the throttle, while the cruise control is on, the braking system activation by the cruise control is disabled, at least until you let up on the throttle again and let the cruise control resume its job.

I would suggest you don't bury your foot on the throttle going downhill with the cruise control on, but if you do, don't fight it, you're gonna get lots of technology come to your aide.

Personally, I think they made a well thought out system and it works well.

If you don't want the brake system to activate by the cruise control system, turn it off and coast to your heart's content! And if you want some really good coasting, put it in neutral.

We got what we paid for, a car full of technology!