In this thread, I noted some differences in the way the cruise control (CC) functions in our two cars:
I have noticed that the cruise control works very differently between the standard CC in my wife's 2014 and the adaptive CC in my 2013. Going downhill in the car with ACC, the set speed is essentially maintained, however, with standard CC, the car tends to run away, picking up a significant amount over the speed limit on some downhills.
I ran a little experiment with the cars on a short, but fairly steep hill near my house. Both cars have ECO Cruise set to ON. Initially, I believed the difference in performance was due to one car being equipped with Adaptive Cruise Control (ACC), and the other car standard CC. Now, I'm unsure if that's a reasonable explanation. Both cars have 17" wheels with tires inflated to 38 PSI. Except for the ACC feature and model year, the two cars are virtually identical.
For each run down this hill, I set the CC to 40 MPH, and made sure that I was at that speed as I crested the top of the hill from the far side to the downhill test area. I touched neither the accelerator pedal, nor the brake, until reaching the bottom.
Car #1 - 2013 FFH SE w/ ACC (mine)
ACC ON - Actual vehicle speed increased to 42-43 MPH while descending, and regenerative braking automatically kicked in until the road began to level off at the bottom of the hill, which obviously helped the vehicle maintain a speed close to the set speed.
ACC OFF - Performance was exactly the same as with ACC ON.
Subsequent runs with Grade Assist (GA) turned ON did not have different results, as this feature did not seem to actually engage. I'm assuming that this is because the automatic regen braking kept the vehicle speed below the threshold at which the GA feature engages.
Car #2 - 2014 FFH SE w/ standard CC (my wife's)
Actual vehicle speed increased to 54 MPH while descending, and regenerative braking did NOT kick in at all.
A subsequent run with the GA turned ON at the top limited the vehicle speed to 45 MPH.
I first noticed this difference just after purchasing my wife's car, as I was driving it home. While heading down a different hill on a highway, I suddenly realized that I was traveling much faster than planned. My 2013 had kept me out of trouble on this hill, but the 2014 was moving a good 20 MPH over the speed limit before I realized what was happening. Every once in a while, when driving my wife's car, this difference in functionality still catches me by surprise.