I've had the same questions as well but mostly because I've not read that part of the manual yet. 
I did try that option before posting it here, but the manual doesnt talk about the exact functionality of the +-5 mph setting.I've had the same questions as well but mostly because I've not read that part of the manual yet.![]()
I will try to pay attention next time I drive, but I believe what is happening is when I am driving at 50 speed limit with setting of +5 and I set it to follow the speed limit it will set on 55. When speed limit changes let's say to to 65, I get a notification with an upward arrow flashing as well as the speed limit flashing as well. I have to then adjust on the steering wheel the speed up (one long push up) and it will adjust to 70 (65+5). Will confirm next time I drive...So I have set the speed settings to stay 5 miles above the current speed limit under the HDA settings, but the only thing that it does is when the speed limit changes, it prompts me to press the up/down arrow to set the speed +5mph as per my setting. An example :
Lets say i'm driving at 70 Mph with cruise control set on a freeway with a speed limit of 70, and my HDA icon is fully green. Now when the speedlimit changes to 75mph, shouldnt hda automatically update the cruise control speed to 80mph based on my setting? What I observe is that it only sets the speed to 75mph i.e. the exact speed limit and does not honor the +5mph setting i've made.
Is this a bug? or am I just not clear about how this feature is supposed to work?
Thats my exact experience too, But apparently from the description on the cluster, I thought it should automatically adjust to 70(65+5) when hda is all lit up and also 'Highway Auto Speed Change' is enabled. It works when driving speed matches the speed limit on freeways, i.e .if cruise control is set to 70 and the speed limit is 70, and then the speed limit changes to 75, it will automatically change the cruise control speed to 75. I was just hoping that it could set it to the +5 offset that i've set.I will try to pay attention next time I drive, but I believe what is happening is when I am driving at 50 speed limit with setting of +5 and I set it to follow the speed limit it will set on 55. When speed limit changes let's say to to 65, I get a notification with an upward arrow flashing as well as the speed limit flashing as well. I have to then adjust on the steering wheel the speed up (one long push up) and it will adjust to 70 (65+5). Will confirm next time I drive...
The more I drive the car, and the more I read this forum, I realize how much I still have to learn and research about the car.Thats my exact experience too, But apparently from the description on the cluster, I thought it should automatically adjust to 70(65+5) when hda is all lit up and also 'Highway Auto Speed Change' is enabled. It works when driving speed matches the speed limit on freeways, i.e .if cruise control is set to 70 and the speed limit is 70, and then the speed limit changes to 75, it will automatically change the cruise control speed to 75. I was just hoping that it could set it to the +5 offset that i've set.