kfhughes

I'm lurking on here as a 2006 TL owner who's considering switching to the RDX. One of the things I've never liked about the 3G TL is the cruise control. Works fine on the flat or on uphills, but on downhills it doesn't even try to maintain a constant speed (geez, even my 1999 Dodge Intrepid did that). We do a fair amount of driving in the mountains, but we're far enough away that a test drive is not feasible.

So would like to tell me if I can expect this to work better on the RDX, or am I in for more of the same?

hawkeye62

I don't know of any cruise control that limits speed on a steep down hill. All a cruise control can do is set the throttle to idle. (I don't know of any that use the brakes or shift to a lower gear.)

Jim

kfhughes

Our 1999 Dodge Intrepid ES would automatically downshift on downhills to keep the speed steady. It was pretty nice.

Domm

My c300 keeps a constant speed throughout and downshifts to maintain a constant speed going down hills. Come to think of it, my old corolla did the same as well. No idea of whether the RDX does it, but I'm sure it does.

hawkeye62

I learn something new everyday on this forum!

Jim

parasitius

Yeah I always thought if only for liability reasons the cruise control doesn't let you roll down hills (I wish it did sometimes ... ) because if you got a speeding ticket when you had supposedly "set" your speed exactly to the limit...

mikejmack

I noticed a downshift on a downhill in cruise on a recent trip, so I believe it does attempt to decelerate. It's not perfect, but does help to slow it down a little.

GRDX

If you don't want the cruise control to hold you back when descending a hill just push the CANCEL button. Push RESUME once the car slows back down to your desired speed. Of course if it gets going too fast for your comfort you may need to use the brakes :-)

parasitius

I tend to totally forget about the existence of resume since it doesn't work 90% of the time (going from a stop light) ... but it would work quite good on hills -- yes -- good idea, thanks.

markonibre

never payed to much attention to that... until now....i took longer time to get to work this morning so i can test that out....
had my cruise set to 60.....going downhill (medium hill) it maintained 60 on the dot....but if it is really steep i can see it going up to 65...
......it will not be that exact speed that you' ve set but it will try its best to maintain it and the car does shift down.....
my view of the test i did this morning

juice13

So short answer to you question is the system works well.

Long answer:
I would go as far as to say the cruise algorithm is a little too eager to maintain set speed as the incline increases.

First, the variable cylinder management will turn off (or reactivate all cylinders) for more power. I can feel this. It is usually very subtle, almost like a soft gear change. It is easy to see in the instant MPG screen. It may also adjust throttle to maintain speed.

Then, if firing on all cylinders and adjusting throttle doesn't keep the speed at constant (or at least within around 2%) the tranny will kick down to 5th gear.

Sometimes if the hill was steep and sudden, the car will slightly over accelerate and you may find yourself going a little faster than planned up the hill. Downhills are easier to modulate with engine braking and I haven't seen any issues maintaining a constant, set speed.

This all happens pretty smoothly. I imagine the engineers spent a lot of time tweaking this.

We have had the car loaded down driving through WV and actually had the car kick down into 4th to maintain 80mph up a very steep and very long mountain highway. A little buzzy, but the car was just doing what I told it to do the best it could.

Sometimes for fun I'll anticipate the hill and paddle shift down a gear to help the car keep speed, but this isn't necessary.

On my BMW, the twin turbos render moot any need for (manual) downshifting.

Mikey Dallas

I have been on several trips with my 13 rdx and found the cruise to maintain speed very well. On another note, what I really like is the "accelerate", "decelerate" buttons add exactly one mile up or down with each push.

robuckj

After driving an MDX for 7 years, and now the new RDX, I would say the RDX does *almost* as well as the MDX (which was very good) in keeping a steady speed up and down hills. However, I have noticed the RDX does seem to speed up going downhill on occasion--not all the time, not most of the time, but some of the time.

I once drove a rented 2005 Buick Lucerne from Washington, DC to Springfield, IL, and after awhile I had to just turn the cruise control off because it was so unsteady. Compared to that, the RDX cruise control system is absolutely fabulous.