We were out on our maiden drive on our new Subaru. We were traveling south on I-5 through southern Oregon into northern California, over the highest point on I-5. Light to moderate traffic, with a high percentage of tractor/trailers. Trying to drive smoothly without heavy braking to avoid vehicles pulling out in front of you to pass tractor/trailers. I was trying to use the +/- button to modify my speed as needed to accelerate and decelerate around traffic, without having to use the cancel button or braking. (I do this all the time in my Honda - works well). I often found that the "set" speed did not respond to the commands I gave it via the +/- set button. I am driving along hitting the - portion of the set button and finding that I am NOT SLOWING DOWN nor is the "set" speed responding. Then I am forced to hit the brake to avoid an accident.

After the first couple of times of not understanding what is going on and having to hit the brake to avoid an accident, I started to play with this button. I found that about 30-40% it responded as I would expect, and about 60-70% of the time it did not. Basically I would hit the +/- button and the set speed would not modify. During this test I was traveling down hill in a curvy river canyon.

Anyone else seeing this problem? I am new to this vehicle, and there may be some differences in the way that this cruise control works relative to my Honda Accord, and other vehicles that I have driven.