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AP v8.0 Review: Driving in Heavy Rain

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Got home a while ago after a 2hr drive through continuous heavy rain here in the bay area. Speeds ranged from near standstill to 70ish. Visibility ranged from decent to poor (couldn't see 3-4 carlengths ahead) . I drove with AP enabled as much as it would stay on. Except for a 10 minute period through driving rain when it disengaged and would not turn back on, it worked very well. During the period where Autosteer would not work, TACC still worked fine. There were two instances where the AP 'lost' the lane marker dots (the lanes themselves were barely visible in the nighttime rain) and wandered into the adjacent lane. I let it wander while keeping track of the next lane, before bringing it back into my lane. Acceleration and deceleration were not jerky. I kept the spacing in front at 4 throughout, which was plenty. Overall, my experience follows this article: Tesla Autopilot Performs Surprisingly Well in Heavy Rain
 
I have not driven with AP v7.x in such heavy rain, but with what the car has in v8.0 today, I'd happily use it in such conditions. It's more effective than I thought it would be, able to accurately track the lane and cars around in heavy rainfall conditions where I had to focus to see everything around myself.
 
Same weather system...

I did a drive in moderate rain from the SF Bay Area to Fresno this morning. The rain stopped somewhere around the I-5 / CA-152 interchange (which is just south of the under-construction Santa Nella Supercharger), and I had AP engaged almost the entire time. So I got a fair bit of experience with AP 8.0 in rain. In general I was impressed at how well it tracked the lanes and stayed centered, even in curves. There is one curve in particular (eastbound I-580, Altamont Pass, going under UPRR tracks) where I always had to take over steering on 7.1 and earlier, but 8.0 was rock solid.

There were a few places where I disengaged autosteer to maneuver around traffic, and it didn't have enough confidence in the lane markings to allow me to reengage immediately. But once I did get autosteer engaged, it stayed on, even with the slightly limited visibility. TACC (on a setting of 3 or 4) was smooth throughout, as I have experienced in better weather.

One stretch of road (I-580 southbound, just south of the I-205 split) is currently under construction...there are stripes between the two southbound lanes, but no lines for the shoulders (there are, however, traffic cones). I was actually amazed at how well it was able to do with only one set of striping to work with...it even displayed the road edge on the IC (no lane markings). I am not sure how it figured out where the road edge was.

Bruce.
 
Drove through torrential rain again yesterday evening on the I80 . I'm currently on V8.0 2.50.114 (AP V1 hardware) . It worked great, and this time I did not have a single instance of AP refusing to re-engage despite visibility being quite poor amidst heavy winds and sheets of rain. Further, the car never lost the lane markers at any time, even though on multiple occasions it 'hunted' to stay within the middle of the lane, drifting left and then right but ultimately centering. This was the case soon after negotiating curves, when I assume the computer vision system tried to keep tracking the change in curvature and then straight road, correctly in low visibility.

This is a noticeable improvement over my last experience with AP in rain back in October. I also noticed that acceleration after slowing down for a car in front is more gradual now. I noticed this when the car in front switched lanes, giving me clear passage, but it didn't accelerate like a jackrabbit as it once used to, either on dry pavement or in the rain.

Overall, I'm pleased to note the continuous improvement in the system under critical usage conditions, even though as AP2 is rolled out, AP1 would supposedly receive less attention. It's the coolest thing about this car - something you bought that keeps continuously evolving.
 
Update. I have a 75D with AP1 v8.1 2017.42 , and my car is uncorked. Drove ~100 miles in heavy rain last two days, both during daytime and after dark.

The car's performance is excellent in these conditions. Despite the rain sensing wiper running at seemingly 200 strokes/min, AP stayed engaged. On a couple of occasions, I had to disengage, and on those occasions, AP took a few minutes before being able to re-engage again. Maybe it's just my imagination, but inter-car separation seemed a little longer with distance setting 3 or 4 compared to what I recall it being in good conditions, almost as if AP is smart enough to elongate car separation in inclement weather.

With the much more evolved AP since that time, acceleration and deceleration were smoother than what I recall last winter. In terms of energy consumption (I have 19" tires with Michelin Pilot Sport A/S 3+ all having ~7/32 tread) over a 100 mile stretch with rainfall about 70% of the way increased from the ideal ~103-104% I see while doing 73-75mph, to 110% - about the same as what I've seen in the past on a really windy but dry day.
 
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