Cruise Control Down Steep Inclines

[BlueValour]

The cruise control works just fine is normal driving with the car accelerating and braking as necessary to maintain the set speed. However, going down particularly steep hills results in the car progressively increasing in speed due to insufficient braking. Is there a known limit to the steepness of inclines for which the cruise control is designed to function?

[timberwolf]

Have you looked in the Owner's Manual? It is mentioned in the USA 2007 OM, it is a bit vague on steepness (and I'm far too lazy to get dressed and go out to the car to thumb through my paper copy of the OM):

"Your cruising speed can be maintained up

or down grades within the limits of hybrid

system performance, although a slight

speed change may occur when driving up

or down the grades. On steeper hills, a

greater speed change will occur so it is

better to drive without the cruise control."

---

CAUTION

D To help maintain maximum control

of your vehicle, do not use the

cruise control when driving in

heavy or varying traffic, or on slip-

pery (rainy, icy or snow ­covered) or

winding roads.

D Avoid vehicle speed increases when

driving downhill. If the vehicle

speed is too fast in relation to the

cruise control set speed, cancel the

cruise control then shift the shift

lever to "B" position to use engine

braking to slow down.

[kithmo]

The cruise control works just fine is normal driving with the car accelerating and braking as necessary to maintain the set speed. However, going down particularly steep hills results in the car progressively increasing in speed due to insufficient braking. Is there a known limit to the steepness of inclines for which the cruise control is designed to function?

AFAIK the Cruise control is not adaptive, i.e. it doesn't brake to slow the car down. It just lets off the accelleration, which results in regenerative braking to the same degree as when you take your foot off in non-cruise mode, but no friction braking occurs. Putting it in "B" would add engine braking to the deccelleration phase.