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

Autopilot slowing on tight corners


Dec 2, 2017
UK, US and Europe!
Today I was using Autopilot on a windy mountain road (in Germany) and was amazed at how my model X knew exactly how much to slow down for each corner and took perfectly (I was ready to take over whenever not comfortable), but only hairpins could it not handle and I had to manually take over.

Does anyone know how this works? Does it use GPS and map data, or has it learned from the speed of previous Tesla around the corners?

Later in the journey in the Czech Republic the car did not seem to know to slow down for corners in an area where it had no internet connectivity - so it must be getting this knowledge over the air.

I found it fascinating. We may want FSD to arrive soon, but in the mean time I marvel at what Autopilot is capable every time I drive - although am not complacent, or over trusting and are always ready to take over.
  • Like
Reactions: tpham07


Former Vendor
Nov 6, 2017
Lakeland, FL
I'm not exactly sure what methods they are using but I'm thinking it's a combination of GPS and an accelerometer. If you noticed it does it both on AP and TACC. Whenever I turned a little tighter around a corner increasing the G-force it would slow down even more that's what is making me think it may have an accelerometer.


Active Member
Mar 24, 2015
map data i believe.
mostly works well, but occasionally there are curves that are not recognised for limiting speed, and that's when you need to remember it is Level 2 assistance as it happily barrels into a 40mph curve at 60!


Dec 2, 2017
UK, US and Europe!
Exactly, the danger is becoming over confident in Autopilot. For example on my journey it could not handle hairpins - there seems to be a limit to how tight corner Autopilot can handle. The thing is to enjoy its use, but be aware of its limitations and ready to always manually take over. The people that have become over reliant on Autopilot, are the ones that have have come to grief.
  • Like
Reactions: Bogobec


Aug 22, 2018
Manchester, UK
On a on ramp that went 360 Deg round on itself it gave up the ghost and nearly hit the barrier luckily I was paying attention. Maybe V9 will have sorted these issues?


Active Member
Oct 2, 2017
UK, Milton Keynes
I believe it's linked to map data. It's not very reliable here in the UK. Slows for some corners reasonably well, totally ignores others or doesn't slow enough. Also brakes approaching certain roundabouts, but not all. It behaves consistently at specific map locations, so I guess it has a speed database linked to the map, but not fully populated. As others have mentioned it also seems to slow as you apply steering lock, so could be using a simple steering algorithm too or possibly an accelerometer.

Products we're discussing on TMC...

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.