Re: Is this a joke
That isn't how it works. If you had previously set the TACC to 85mph max speed then it would go back up to that speed. However you would already be breaking the speed limit.
If you were in a 50 and enabled TACC then that is the maximum it would speed up to after that point. It doesn't increase your maximum set speed limit. This limit is set at the point when TACC is enabled or manually adjusted.
Think of normal traffic aware cruise - you set to cruise at 50mph and it can slow down due to traffic but it won't suddenly speed up past 50mph.
The TACC can slow down, it can't go over your set maximum.