I've now used ACC (TACC) on three cars, 2010 BMW 650, 2012 BMW 650ix and Tesla P85D. The best and most consistent is the Tesla. I use it in rush hour stop and go, on highways or on roads I need to stay in a reasonable speed range to not get a ticket. The Tesla TACC has better acceleration from a stop than the BMWs, meaning it mimics more closely how I accelerates. In stop and go it does a great job of stopping in plenty of time and when stopped stays active for a longer period of time than the BMWs. The Tesla system has surprised me in most cases it has recognized stopped cars. I never expect that to be 100%. There are just to many variables. The only weakness I've experienced is when changing lanes the TACC starts to accelerate then stops the acceleration too soon as if it wants to go but sees the car in front and slows. This may be a function of the software I'm still running 2.4.236.