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Autopilot — left bias

Ok folks, maybe someone can help me out here or put my mind at rest.
My wife complains that on the motorway she feels like the M3 on autopilot doesn’t leave enough space when passing a vehicle on the left.
I’ve noticed that when on Autopilot the car likes to sit about 10-15% further left than the middle of the lane. That’s true even on the on-screen display: it’s subtle but you can see that it likes the left hand side.
How does your M3 behave on autopilot? Does it prefer the left of the lane? A couple of times I’ve had to yank it and take over because it was leaving just inches between me and the car I’m overtaking.
 

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I believe it’s because we all instinctively hug the right of a lane without knowing it, because we sit on the right hand side of the car and can’t judge with much accuracy where the left side of the lane really is.

My tesla hugs the centre of a lane as far as I can tell when looking in the side mirrors.
 

thegruf

Active Member
Mar 24, 2015
2,318
2,116
indeterminate
MS AP2.0 - have the same complaint from the passenger.

If you looking the side mirrors actually the car seems (mostly) in the centre of the lane, although very difficult to judge, so one answer is that the car is correctly centred but naturally the driver moves slightly to one side when passing large vehicles and AP sadly has yet to learn this behaviour.
The other answer is I have always wondered if Tesla have got an error with RHD where the slight offset from centre (if there is one) if added in the wrong direction ie should be inverted for RHD vs LHD.
This is somewhat corrobrated by much earlier versions in AP1 days having "truck lust" where they would clearly lurch towards the left when passing vehicles, I suspect Tesla backed off on moving from the lane centre due to lower accuracy in those days, but definitely the movement was in the wrong direction at the time.

I have a similar concern with AP following distance, it is clearly closer on single carriageway A roads than Dual Carriageways, and I wonder if they are miscategorised somehow in hte UK.
 
Bias seems to vary often between software versions. I've had a very left bias before after a windscreen replacement, confirmed by TeslaCam side view recordings which self corrected itself possibly after a firmware update. A camera recalibration when about to drive on some well marked roads is worth doing if too much of an issue even if to dismiss that.

Sometimes a check of rear view cameras can disprove what in car visualisation is showing/occupants are feeling.
 
Last edited:

Billbrown1982

TM3 LR 2021 | Red | FSD
Dec 21, 2020
611
351
Basildon
Mines pretty good honestly. I would suggest a camera recallibration and see if that helps any.

Also try driving with the cameras up on screen and you might find its not as bad as you thought.

That said, i've always been moaned at by passengers for driving too close to the left long before I had a Tesla so .... yeah maybe you should just forget everything I have said!
 
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Mine sits further to the left than I’d prefer, especially when passing another vehicle. Why it can’t shift over to the right slightly when overtaking is a mystery to me.
It does shift over slightly when passing lorries. It's subtle, but if you keep a close eye on the lines it does do it. For the rest of the time, it's pretty much centred its just most people subconsciously sit a bit to the right as that's what side of the car they're on.
 
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It does shift over slightly when passing lorries. It's subtle, but if you keep a close eye on the lines it does do it. For the rest of the time, it's pretty much centred its just most people subconsciously sit a bit to the right as that's what side of the car they're on.
It could definitely shift over further! Passing lorries on AP is nerve wracking stuff.
 
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I believe it’s because we all instinctively hug the right of a lane without knowing it, because we sit on the right hand side of the car and can’t judge with much accuracy where the left side of the lane really is.

My tesla hugs the centre of a lane as far as I can tell when looking in the side mirrors.

Definitely that. When you learnt to drive with a RHD car, you tend to stick to the right side of the lane.
My family in Europe, with obviously LHD cars, are the opposite, they stick to the left of the lane. Hence why I think it's correct that the OP is talking about a "left bias" for cars designed in a LHD country.

Funnily enough, when people are getting used to drive in the UK with a RHD, they tend to get way tooo close to the left of the lane. Crazy close.
 
Ive noticed a more left bias since on of the recent SW updates. There is a particular point on a regular journey I make that involves some concrete barriers on the left and autopilot makes we wince now it gets to close to them.

Amusingly where I would like an autopilot left bias i.e. where a single lane turns into a dual carriage way, the car typically gets in the right lane instead of the left by default, meaning I have to take over to 'correct' the situation.
 
When I first started using autopilot I always felt that the car was lurching over towards the left as soon as I engaged and that it was getting way too close to the kerb/left side. I then came to the conclusion that autopilot was actually just centring the car in the lane and that I had an unconscious bias to drive slightly right of the lane centre. As to whether autopilot is really keeping to the lane centre or going left of centre - someone must have film of driving behind a Tesla in the UK on autopilot that would answer this?
My guess, until I see evidence to the contrary on film, is that autopilot really is driving the car in the centre of the lane and the feeling you are too far left is psychological and arises because we typically tend to drive off centre closer to the right side of the lane. Do people in countries that drive on the right feel that autopilot jerks them to the right when they first engage it?
 
I think AP centres the car but also in curving highway roads allows the car to drift to the outside edge a bit to smooth out the corners, which does bring it closer to the left of centre. I naturally find I drive slightly to the right of actual centre most of the time, primarily to avoid the rough edges, debris and overhang at the curbside and to increase distance from vehicles I’m overtaking to reduce risk of side impact within my reaction time. Occasionally I do find myself disengaging AP because it is left enough for me to sense it as dangerous, but that tends to be on non-highway roads. Perhaps this might change with the FSD Beta.
 
As to whether autopilot is really keeping to the lane centre or going left of centre - someone must have film of driving behind a Tesla in the UK on autopilot that would answer this?

Its really easy to see from in side the car and record it for playback later. Use the TeslaCam output from rear view with both rear facing side cameras active.
 

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