# Forums

## Noob question (AP "MAX" speed)

I noticed, when running in AP (or NoA) that speed is capped "MAX" and that cap varies with location and outside temperature. I was also reading a post in another forum that that person's M3's "MAX" was first reduced to 70 mph and then 65 mph on a highway journey into AZ, where the temperature was 124 degrees (YIKES!). What determines this variable "MAX" speed on the M3?

jjgunn | August 15, 2019

Pretty sure it's 90 MPH

Joshan | August 15, 2019

On a non-divided road the cap is speed limit +5. On any divided road it is 90 mph.

jebinc | August 15, 2019

@Joshan and @ jjgunn - If that's true, how do you explain this poster's experience?
https://teslamotorsclub.com/tmc/posts/3925848/

jebinc | August 15, 2019

^^^ P.S. I've noticed the +5, but I've also seen a 45 MAX change to 44 MAX, so ?

Joshan | August 15, 2019

cant say I have ever seen that. you sure you didnt roll the thumb wheel down one mph and set it to 44?

Joshan | August 15, 2019

If you see it again please roll the thumb wheel up to max so you get the message that you are at max speed and take a picture of the screen.

jebinc | August 15, 2019
Joshan | August 15, 2019

ya he has it set to 65, that is not the cars max. It is the drivers max.

jebinc | August 15, 2019

@Joshan - I took it as his car lowered the MAX due to heat and battery preservation. Guess not.

Effopec | August 15, 2019

I'm in Dallas, and while I haven't seen 124°, I have never seen a heat warning. My guess is they either rolled the thumbwheel down without knowing it, or they didn't have sufficient battery to reach the next SC.

jebinc | August 15, 2019

@Effopec - I think you solved it as there was talk about maybe not having enough juice to make it to the next SC station...

Joshan | August 15, 2019

I have never heard of or seen a Tesla lower the speed based on temperature or battery.

If you have a route planned and it has a super charger stop and you are not going to make it, it will tell you to slow down. I have had this happen. But it is just a message, it doesn't actually lower your speed. It told me to lower my speed to 65mph or I would not make it to the next Super Charger.

Any longer time owners want to chime in on that?

EVRider | August 15, 2019

The OP isn't talking about the absolute max speed, which is 90 if you're using Autosteer (depending on the type of road).

@jebinc: I don't think the temperature has anything to do with it. The "max" speed (which isn't really the maximum speed) is based on the speed limit, type of road, and the speed limit offset specified in speed assist. Once you actually engage AP or just TACC, you can adjust that "max" speed up or down. I'm not sure why Tesla chose to call it "max" speed.

Joshan | August 15, 2019

you cannot adjust it more than +5mph in AP though on a non divided road. That is max AP speed.

EVRider | August 15, 2019

@Joshan: Correct, and if the car can't determine the speed limit, it uses 45mph (which gives you an absolute max of 50).

Joshan | August 15, 2019

I did not know that about the default. thanks!!