# Impressions on Cleveland-Asheville trip



## francoisp (Sep 28, 2018)

I thought I'd share a few unexpected and undesirable behaviors of Autopilot.

1) on 3 occasions, after initiating an automatic lane change, the car jerked back into its departing lane for no apparent reason. There was no car around me, or objects on the road and the white lines were well painted.

2) on 2 occasions, after successfully completing an automatic line change, tye car would refuse to accelerate to its preset speed for an unknown reason. There was no car in front slowing us down, just a large rig that I was trying to pass.

3) on one occasion, as I was driving in the right most lane, the car in front of me took the exit ramp to get off the highway and my car abruptly decelerated *after* the other car was already out of my lane.

4) on one occasion, I had a phantom braking incident at 75 mph. Fortunately no one was behind me.

5) the car often suggests changing lane for no apparent reason. I can't see putting that feature on automatic. I've even had situations where in a construction zone with a single car lane, the car would suddenly suggest changing lane. I was almost tempted to accept the recommendation to see what would happen.

On a positive note, the drive was very relaxing, the car having driven 99% of the miles. I could enjoy the scenery a bit more. The automatic lane change makes changing lane safe and easy. Charging stops are quick and not burdensome at all although I whished the superchargers were closer to the highway.


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## garsh (Apr 4, 2016)

1) That seems to happen when the car detects a car approaching from behind in the lane you're changing into. It doesn't matter that it's far, far behind, and you would easily complete the maneuver in time. Quite annoying.

2) I haven't noticed that one.

3) Yep, it seems like the car isn't sure that the car on the off-ramp is completely out of your lane, or that it's worried that the driver will change their mind and dart back onto the road. Either way, quite annoying.

4) It's been a long time since I've had a really bad phantom braking event. I still get them, but now they're just minor slow-downs rather than a hard deceleration.

5) I get this all the time. And I agree - I keep NoA lane changes in "confirmation required" mode. It makes too many wrong/dumb decisions.


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## Ed Woodrick (May 26, 2018)

1. The car did see something, it just didn't tell you. 

5. No apparent reason is mainly because you don't understand it's algorithm. In general, if it can see a car in front or behind (when in the let lane) it will change lanes. Most people only change lanes when you are getting close to cars.


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## francoisp (Sep 28, 2018)

Ed Woodrick said:


> 5. No apparent reason is mainly because you don't understand it's algorithm. In general, if it can see a car in front or behind (when in the let lane) it will change lanes. Most people only change lanes when you are getting close to cars.


Its algorithm is sometimes right, sometimes wrong and sometimes very wrong like my one lane construction zone example.

It can also be pretty dumb. For example my car systematically asks me to change lane when nearing a bridge in my locality. That bridge has an offramp and no re-entry but the car doesn't factor that in it's algorithmic decision tree.


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