Big Jay E

I have a mild down hill section of highway on my way to work. With the cruise on 64 mph ( 55 limit), it feels like it keeps hitting the brakes. My C5 doesn't do this.

2010 GS A6

george vee

I would think that it is using the a6 trans to slow it down

dgrant3830

I really doubt it would actually use the brakes. Its possible that the AH/TC system is coming into play, but its probably a safety item to activate those systems for normal driving conditions.

etaylor14

It definately does not use the brakes....

widgetsupply

I don't think a Corvette uses the brakes either. However, there are cars that do. I have an Acura MDX with Adaptive Cruise Control. As you approach a car, the system uses the brakes to slow you down keeping you at the following distance you choose. When the slower car gets out of the way, it speeds back up again. Sometimes I wonder if people following me think I am an idiot because I am on and off the brakes. lol

TBIRD57

my c6 has cruise control?

j_digi454

The Vette does not.



Correct, my BMW X5 does use the brakes and you can definitely tell.

Wayne O

To the best of my knowledge cruise control adjusts the throttle only to maintain the desired speed. No brakes.

That would drive me crazy (no pun intended). I prefer driving my car...being in control of my car. I don't want my car to drive me.

indyjack18

I was thinking the same. My GS m6 maintains the set speed even on long downhills. My Avalanche is like a run-a-way freight train

mforman42

It doesn't use the brakes, but the A6 may downshift. The tell tale would be an increase in the revs...

My Jag XF downshifts to maintain speed on steep downgrades.

swifty

Wifey's Accord uses throttle and tranny to reduce speed on a downhill after one or two braking excursions - not cruise-control related I don't think (although I have probably been on 'cruise' each time I noticed it). You can see the revs increase so I know it's tranny related, but I've never felt/ seen (by indicator lights) a true 'downshift' - feels more like brake application - so I know what the OP means.

Don't know exactly what it's doing and haven't taken the time to RTFM for her Honda yet 'cause I'm busy reading 'Vette material. So-o-o-o-o- just enjoying the not-understood function engineered in by Honda. Does the 'Vette A6 have the same function?

JoesC5

I don't think so. On most hills the engine's compression seems to hold the speed down. Some steep hills and the car does exceed the limit I set.

My Mercedes will automatically downshift the transmission on steep hills.

Big Jay E

OK good. I try to use the brakes on this car sparingly as I imagine they are very expensive to replace.

I thought if the cruise was doing it, I would quit using it. This car does have a rather abrupt "throttle chop" if you have it floored, then let off. Maybe that is what I am feeling.

The RPM does not change as though the trans was down shifting.

Mad*Max

It doesn't use the brakes, although like others mentioned some vehicles do use the brakes.

widgetsupply

I wonder if it could be cutting gas to create the slowdown somehow. I know if I hammer it and abrubtly step out of it, the deceleration is almost as strong as the accelleration without touching the brakes. My wife has accused me of trying to give her whiplash. lol.

Bill Dearborn

If its a slight downhill grade I imagine what you are feeling is the throttle cutting on and off as the cruise tries to maintain speed. With the TCC locked up you have a direct drive connection and you will feel the engine cutting in and out. I feel it on my 6 speed manual and all of my Vettes with manual transmission and cruise control have been that way since I bought my 86. The difference between your C5 A4 and the A6 is the big difference between gear ratios. Due to that the A4 probably de-clutched the TCC more often than the A6 does and torque convertor slippage reduced abruptness of the throttle changes.

Bill

Chevy Cust Svc

Like others have mentioned, when using cruise control on a hill, the car should not automatically apply the brakes under normal driving conditions. Possibly there is a traction or stability event occurring that would apply the brakes.

Thanks,
Laura
GM Customer Service

c1vettes

My wife's 2010 Cadillac Dts platinum has the adaptive cruise control which does brake when the cruise control is on and we get too close to the vehicle in front. My 2009 Vette does not brake when a similar situation occurs.

Interestingly the Cady has the option and the Vette does not. The Cady listed out at about $64K and the Vette $73K. One wonders?