Here's one interesting thing I've noticed since activating the FSDb option last month:
My Tesla's speed readout used to register significantly high, like 6% or more. If the speed readout claimed 45 mph, the real speed was typically 42 mph. I noted this based first on my own judgment, then confirmed it with a couple of roadside speed-radar displays, and further verified it using one of the commonly available GPS-based Android apps. I wondered (and still do) why Tesla didn't run a background calibration routine using its own built-in GPS.
After switching to FSDb, I noticed that the car now feels faster for the same speed setting, traveling the same familiar roads. Again I broke out the GPS speedometer app and sure enough, 45 mph on the screen now typically reads 44 mph. This may not seem like a big deal, but it's actually pretty noticeable when you commute the same route every day.
The next question, of course, is why does it still indicate just a bit high, and not right on true speed? - which again, the car is perfectly capable of calibrating within the integer-mph readout resolution.
I just watched Dirty Tesla's 2020 vs 2023 FSDb comparison video*. At 10:07, he mentions the NHTSA-mandated elimination of rolling stops, but with a detail I hadn't recognized before: Even though the car on FSD does achieve a complete zero-mph stop, the speed readout shows 1 mph at that moment. He says NHTSA also mandates that the speedo should not indicate a lower speed than actual; the inevitable result of such a policy is that it's set with a slight ~1mph bias to err on the high side.
I did a quick search and couldn't find a clear reference to such a rule, but I found this webpage on the topic:
Are speedometers designed to read high?
Anyway, the bottom line is that the FSDb stack definitely improved my car's previously significant speedometer error.
My Tesla's speed readout used to register significantly high, like 6% or more. If the speed readout claimed 45 mph, the real speed was typically 42 mph. I noted this based first on my own judgment, then confirmed it with a couple of roadside speed-radar displays, and further verified it using one of the commonly available GPS-based Android apps. I wondered (and still do) why Tesla didn't run a background calibration routine using its own built-in GPS.
After switching to FSDb, I noticed that the car now feels faster for the same speed setting, traveling the same familiar roads. Again I broke out the GPS speedometer app and sure enough, 45 mph on the screen now typically reads 44 mph. This may not seem like a big deal, but it's actually pretty noticeable when you commute the same route every day.
The next question, of course, is why does it still indicate just a bit high, and not right on true speed? - which again, the car is perfectly capable of calibrating within the integer-mph readout resolution.
I just watched Dirty Tesla's 2020 vs 2023 FSDb comparison video*. At 10:07, he mentions the NHTSA-mandated elimination of rolling stops, but with a detail I hadn't recognized before: Even though the car on FSD does achieve a complete zero-mph stop, the speed readout shows 1 mph at that moment. He says NHTSA also mandates that the speedo should not indicate a lower speed than actual; the inevitable result of such a policy is that it's set with a slight ~1mph bias to err on the high side.
I did a quick search and couldn't find a clear reference to such a rule, but I found this webpage on the topic:
Are speedometers designed to read high?
Anyway, the bottom line is that the FSDb stack definitely improved my car's previously significant speedometer error.
* I'd recommend this video, not only for tthis arcane speedometer discussion, but generally for its perspective on the FSD beta progress since 2020. Chris also takes the last 5 minutes of this ~19 minute video to give a nice verbal summary of the often-discussed missing i.e. unimplemented basic capabilities and common foibles of the present FSDb system. This reinforces my contention that, while he's certainly enthusiastic and good-natured in his presentation, the "shill" accusation is undeserved. He doesn't shy away from honest assessment of the problems.
"Electric Car Tesla Model S driving in autopilot - instrument panel / cluster shows street camera, navigation system and speed indicator" by verchmarco is licensed under CC BY 2.0.
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