Since V10 came out it seems impossible to set cruise control below 50mph regardless of the type road you are on. I have multiple miles of 30mph surface streets to get to my house and I have to do 4 fast scrolls on the cruise control wheel to get it down to 30mph.

I use TACC on most roads - many under 50MPH, without issue. what do you have your relative/absolute speed setting at?

 

I use relative +5mph for my cruise control speed. I used to use relative -20mph to try and get around this unintended acceleration behavior but then if you use navigate on autopilot the car will adjust to 20mph below the speed limit when switching highways. I think this 50mph/75mph TACC set speed problem is only occurring on roads that don't have a speed limit in the maps database. This screenshot is from a road with a 35mph speed limit. You can see that no speed limit is logged in the maps data and the TACC set speed is at 75mph. Autopilot is available on this road and if I turn it on it will activate at maximum "no speed limit present" speed of 45mph. When I turn off this road onto neighborhood streets the TACC will adjust down to 50mph set speed. This problem seems more prevalent and frequent in V10 than it was in V9.

 

• Navigate on autopilot reducing speed from 80mph to 48mph before taking a perfectly straight and long exit ramp. I generally override the speed with the accelerator pedal manually but today there was no traffic behind me so I let it do its thing. Slowing to 48mph on the highway before taking a Long and straight exit ramp is dangerous.
• Re-merging: This has been a problem for a long time but it needs to be fix ASAP. Here in Texas the right most lane gets suddenly wider when an on-ramp meets the highway. AP will quickly try to re-center itself in a double width lane when this happens, it's most prevalent when following a car which prevents seeing the highway in the distance. It would be much safer for the car to continue to follow the white dotted inside lane marker. It does this sometimes so you know it can do it, just chooses not to.

These two at least are not new to V10, and yes, I agree they are quite annoying.

Fortunately in NC, onramps are striped right up to the end of the merge lane, but whenever I travel through other states, and in particular VA you get that horrible "centering". The only times I've seen it do it "right" are when there is a tar patch or seam of some kind that acts like a lane marker. My wife and I shrug at every on ramp, but one time in particular it somewhat violently re-centered itself just as there was a car to the left of us, which I imagine was very concerned with what was going on with us. I agree that this needs to be improved quickly.

I would add one more misbehavior which is becoming quite annoying (and is not new to V10), and that is when you manually initiate a lane change out of the passing lane (because the car sometimes refuses to do so on its own, despite cars coming up quickly from behind), the car slows down by 2-3 mph before performing the lane change, even when there is no car to the right. At first I though it was slowing down because I wasn't sufficiently ahead of the car I was passing and it decided it was going to slow to get behind it, but I confirmed recently that there was no car to the right of me when I initiated the lane change and it still slowed down. This is definitely unexpected behavior for cars tailgating you from behind waiting for you to get out of the passing lane.

 

I would add one more misbehavior which is becoming quite annoying (and is not new to V10), and that is when you manually initiate a lane change out of the passing lane (because the car sometimes refuses to do so on its own, despite cars coming up quickly from behind), the car slows down by 2-3 mph before performing the lane change, even when there is no car to the right. At first I though it was slowing down because I wasn't sufficiently ahead of the car I was passing and it decided it was going to slow to get behind it, but I confirmed recently that there was no car to the right of me when I initiated the lane change and it still slowed down. This is definitely unexpected behavior for cars tailgating you from behind waiting for you to get out of the passing lane.

This has happened once or twice to me as well and I agree it is unexpected and makes you look a bit like an ahole to the car behind you. There have been a few other times I thought it was happening at first but it turned out that the car was matching the speed of the new "follow car" in the future lane. I think most of us change lanes first and then slow to the new speed of that lane whereas AP adjusts speed before/while entering the lane. I understand slowing to match the new follow car and it is different from the slow down for no reason lane change scenario you are describing, which also happens.

 

V10 is a glimpse of the future. Certain aspects of the autopilot experience are greatly enhanced such as cars cutting in front of you in traffic produces a much smoother brake response than before. However in the past two days I've had the following problems. Some of these can be scary or at the least very discomforting, especially for passengers.

• Navigate on Autopilot dive bombing the merging process. Uncomfortably fast swerving into the rightmost lane of the highway from the on ramp. This occurred twice with no cars around me.
• Navigate on autopilot swerving to abandon a lane change because the original lane I was in got wider during the lane change process. It would rather center in the original lane than continue with the already initiated lane change process.
• Navigate on Autopilot mistakingly thinking I was no longer on the highway and reducing my set speed from 75mph to 45mph without warning.
• Since V10 came out it seems impossible to set cruise control below 50mph regardless of the type road you are on. I have multiple miles of 30mph surface streets to get to my house and I have to do 4 fast scrolls on the cruise control wheel to get it down to 30mph. Sometimes it'll continue to think I want to go 75mph and set cruise at that speed even though I'm on a neighborhood street. Cancel cruise that was set at 30mph for a stop sign and it resets back to 50mph. This is horrible behavior. Trying to set your cruise at 30mph and having it set to 75mph in a model 3 performance is terrifying if you don't have your foot on the accelerator pedal while setting the cruise control.
• Navigate on autopilot reducing speed from 80mph to 48mph before taking a perfectly straight and long exit ramp. I generally override the speed with the accelerator pedal manually but today there was no traffic behind me so I let it do its thing. Slowing to 48mph on the highway before taking a Long and straight exit ramp is dangerous.
• Re-merging: This has been a problem for a long time but it needs to be fix ASAP. Here in Texas the right most lane gets suddenly wider when an on-ramp meets the highway. AP will quickly try to re-center itself in a double width lane when this happens, it's most prevalent when following a car which prevents seeing the highway in the distance. It would be much safer for the car to continue to follow the white dotted inside lane marker. It does this sometimes so you know it can do it, just chooses not to.
• Navigate on autopilot reducing speed just before trying to merge due to slight curves in the on-ramp. People behind you are not expecting the car to be braking as you approach a highway with light traffic.

I, like you had really bad experiences through the rapid updates that wen't eventually to 12.2. But one week later my car seems to have normalized and now AP and NOA are better than they've ever been. I'd read in several places now that this is a fairly common experience. Almost like a re-calibration that we aren't (should be) notified about. My suggestion to you is that if after several days of driving you are still not seeing improvement, you should seek service support. The speed issues you are having are concerning. I've never seen any of that. You may have corrupt map data.

 

I have a brand new Tesla X and it’s been in the shop with brake problems more than in my own garage!

Can you direct me to a forum or other people who have had this problem

 

Maybe try here - https://teslaownersonline.com/forums/modelx-maintenance/ - I don't know why you posted here first, that forum is just as easy to find as this one.