The regulation calls out 19 vehicle functions which must have physical controls inside the vehicle, with additional requirements about size and usability of the buttons.
Those functions include:
Turn signals
Hazard lights
Horn
PRND gear shifter
Driver assist function, if present
Windshield wipers
Windshield defroster
Power windows
Emergency call system
Power off switch for EVs


Obviously that’s what I do. It doesn’t actually work for me.
Even when the interior of the car is hot as hell from sitting in the sun, dropping the target temp a few degrees makes the fan blow harder. It doesn’t usually max out unless you set it to LO. Yes, automatic control works, but it doesn’t blow freezing air at you at full intensity unless you set it as low as possible, even if it’s super hot in the car.
I wouldn’t be sure that’s the only factor, since in a lot of cars made this century there’s a refrigerant pressure valve to replace the magnetic clutch. The auto HVAC system tells the compressor how hard to pump the refrigerant depending on how cold it wants evaporator side to get.
So I’ve yet to see a car that can intuit what I want the temperature curve over time to be as I get into the car vs when I’ve been driving for a while. There would likely need to be a thermal camera or something to figure that out, in addition to a machine learning algorithm of some sort.
Fun fact: When it was hot as fuck around summer solstice a few years ago (it’s a big celebration here in Estonia) and I drove to Latvia with a mate to get cheap booze, I set the AC to 12C (actually LO, but 12C was the smallest number shown before LO) for the entire trip and that was what I considered comfy that day, because I’d been out working all day and felt completely melted. If you’re a Fahrenheit user, that’s around 53F. I’ve told a couple of people that in relation to how cold I like my car in the summer and I’ve been asked “wtf kinda car lets you put the AC on 12 degrees”. The answer is W211 MB with Thermotronic 4 zone climate control - I was lucky to own that, the base 2 zone climate control in 90% of those cars only goes down to 16C. Felt like space technology for a 2003 car lol
12C? You dont want an AC you want a freezer.