Follow up ... I don't know what to tell you. I went for a test drive and tried various scenarios, TACC, AP, speed limit warning off, display, chime, absolute and relative speeds ... no matter how I engage TACC/AP with a single or double half or full press, the car doesn’t change speed to the desired set speed until AFTER I let go of the ‘gas’ pedal.
The current manual version says:
“Release the accelerator pedal to allow Traffic- Aware Cruise Control to maintain your cruising speed.”
That matches my experience. I’ve had the Model 3 Standard Plus since March, so it’s possible the behaviour used to be different and the complaints here got them to change the behaviour, but the only way I could get the car to “unintendedly” accelerate was to intentionally let go of the pedal
e.g.
1. Driving 45 km/hr, speed limit sign “60”, set point in *grey* circle is 72 (based on +12 offset set).
2. Engage TACC or AP with single or double half or full down press. Blue circle now shows 72, but I’m still going 45 (keeping pedal at same exact position).
3. Continuing to keep pedal where it is, I can maintain 45 indefinitely even though blue circle shows 72. If I depress a bit I can speed up to say 50 or 55. During this whole time I can use the knob to adjust set speed from 72 up or down. Let’s say I want to not speed, I set it to 59.
4. Let go of gas pedal and car accelerates to set speed.
I’m in a Model 3 Standard Range Plus on 2019.12.1.2, but it’s always worked this way for me IIRC from 12.8.5 at least that I remember.