Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Gwgan

Almost a wagon
Aug 11, 2013
3,232
2,599
Maine
TACC (auto-speed) will maintain whatever speed you set but slow down for slower leading vehicles and maintain a speed-graded distance. Lane keeping (auto-steer) is unrestricted on highways but on lesser roads it limits the speed to 5mph over the known speed limit. Theoretical example, I have a range of speed limits on my commute from 25 to 55; I set TACC to 60 and as long as lane-keeping is active the auto-speed is good: slightly above the speed limit when able or slower in traffic.
 
TACC will not automatically adjust your set max cruise speed based on speed limit signs. You can however adust your current set max cruise speed based on the last sign read by pulling the stalk towards you and holding for about 1 sec. This will also take into account the mph offset you have configured in settings.
These scenarios are for when TACC is disabled.
If your car sees a 45mph sign and you are currently driving without TACC on at 30mph. If you pull the stalk towards you then TACC will be set at 45mph. If you were driving 50mph in the same 45mph zone and pull the stalk towards you then TACC will be set at your current speed of 50mph.
 
  • Informative
Reactions: jeffaa

FarmerDave

Member
Supporting Member
Sep 3, 2015
547
315
Central PA
If you are using AutoPilot at say, 55, and the limit drops to 35, the car will slow down to the new limit, plus offset, and then speed back up when the limit rises. Very handy. That does not work when just in TACC. It will not go about your setting.
I see that effect on smaller highways, but not on the Interstate.
 
  • Like
Reactions: loganintx
TACC … on lesser roads it limits the speed to 5mph over the known speed limit. Theoretical example, I have a range of speed limits on my commute from 25 to 55; I set TACC to 60 and as long as lane-keeping is active the auto-speed is good: slightly above the speed limit when able or slower in traffic.

There are bugs, though. I have noticed that the speed limit recognition algorithm is not smart enough to tell the difference between "Speed Limit 55" and "TRUCK speed limit 55" or "END speed limit 55". I have had to disengage auto steer in those cases to allow TACC to go to my set speed on secondary highways where AutoPilot limits speed to 5 over posted limit.

And I also noticed on two lane winding highways, Auto Pilot will slow down for curves that are too sharp for the set speed; usually taking them at somewhat above the posted recommended speed. Very impressive.
 
  • Informative
Reactions: m2s2
I will be doing a lot of highway driving. So if I have tacc and auto steer engaged, am I limited to speed limit +5 or 91 mph on most highways?

AutoPilot is limited to 90 mph anywhere. Auto Pilot limits speed on secondary highways (non-divided, non-controlled access, in other words not freeways) to the posted speed limit plus 5mph, even when TACC speed is set higher.

I wouldn't be concerned about no AP over 90mph. At that speed safety is a concern and your battery will be drained pretty fast.
 
  • Informative
Reactions: m2s2
If you are using AutoPilot at say, 55, and the limit drops to 35, the car will slow down to the new limit, plus offset, and then speed back up when the limit rises. Very handy. That does not work when just in TACC. It will not go about your setting.

It will only do that on secondary roads. It does not do it on highways and interstates. It will maintain whatever speed you have set regardless of the speed limit on highways and interstates.
 
It will only do that on secondary roads. It does not do it on highways and interstates. It will maintain whatever speed you have set regardless of the speed limit on highways and interstates.

Lots of highways are two lanes or 4 lanes without medians and controlled access; sometimes even with stop signals. (CA highway 41, 49, 88, 89, for example) AP applies speed limitations for such roads.
 
When using auto steer in a restricted area, it seems like auto steer remains functional i manually increase speed with my foot over the allowed speed. Is this normal?

Speed control is by TACC and it can be overruled by your foot on the accelerator without shutting off, unlike when you apply the brakes. Auto steer shuts off when you take control of the steering wheel or (I think) when you exceed the 90mph maximum.
 
Speed control is by TACC and it can be overruled by your foot on the accelerator without shutting off, unlike when you apply the brakes. Auto steer shuts off when you take control of the steering wheel or (I think) when you exceed the 90mph maximum.
Correct..TACC will not go over 90mph though you can press the accelerator on your own and go faster.
 

Saghost

Well-Known Member
Oct 9, 2013
8,224
7,098
Delaware
Does anyone else use autopilot 90%+ of the time? I do for highways and 30% on city roads.

Any idea what would happen if let's say a deer jumped in front of the car?

I think - I hope - that automatic emergency braking would kick in. Similar radar is capable of detecting pedestrians pedestrians at 100m, who presumably have about the same radar cross section as a deer.

I haven't read of a test case yet, and I have no particular desire to experiment, but if it doesn't react this way now it probably will at some point in the future.
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top