PianoAl
Active Member
Yes. Like this (slows after the car is past):
That's AP. So far, FSDb hasn't done that.
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What is the dumbest thing your Tesla does?
- Thread starter Mario Veras
- Start date
That's AP. So far, FSDb hasn't done that.
This makes me totally not want to use AP on roads.
vogz
Member
Mine has always read 2-3mph high. Verified with speed signs and GPS speed app on my phone. My 2003 Porsche 911 Turbo is nearly dead on and so is my wife's 2019 Mazda CX-9. 2-3mph @ 50mph is 4-6% high. That's unacceptable IMHO.
BigNick
Infamous Fat Sweaty Guy
Strategic early warranty expiration. By making yuor speedometer read higher than actual speed, it has the side effect of your odometer reaching end-of-warranty faster.
I have two words to address the statement that 'plenty of people use *FSD Beta* happily without issue.': Im. Possible.
Using it on the highway? Sure. No major problems. Using it on city streets to 'autonomously' drive from your house to the store? Baby, you better have both hands ready to instantly take the wheel and your foot hovering over the brake pedal.
What makes you think the GPS app on your phone is any more accurate? You're using that as the standard to judge all these cars but I highly doubt that any GPS app on a phone is claiming super precise degrees of accuracy on speed and/or location.
This is precisely what I think. I’ve had Toyota vehicles before and they all exhibit the same discrepancy with the GPS app. So it’s either the GPS app is inaccurate, or there is some conspiracy from all major car manufacturers trying to expire our warranties sooner than it should. I tend to think that a GPS app, which has no connection to your car’s speedometer, or computer systems, engine or transmission to calculate speed, and can only rely to a connection to satellites hundreds of miles away and make heavy use of math to estimate your location, which is not entirely accurate anyway, will logically have a harder time calculating your actual speed and therefore harder for me to trust.
Modern cell phones have more than enough computing power to trilaterate GPS signals. But cell phone manufacturers are not really trying to maintain a standard of accuracy on par with say, an aviation system, so I don't think they should be held up as some gold standard used to criticize other systems. They're plenty accurate for their purposes. I don't know why anyone is worried about a 2-3 MPH variation anyway. I can honestly say that in all the years I've been driving I've never been worried that I was 2 MPH over or under where I thought I should be.
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I would bet that most modern cars are using wheel revs in combination with GPS to derive their speed.
vogz
Member
Did you miss where I also said speed signs? That's calibrated Police RADAR. The phone "speed" perfectly matches what the RADAR speed reading is. So, I'm not just using my phone. I'm also using Police RADAR.
4 of these things say the same speed (Phone, RADAR, CX-9 and, 911 Turbo). The only one that's different is my Tesla. It also seems other people have the same issue.
EDIT: I've also used my Dragy unit to verify speed and it has confirmed the same thing. My car displays a speed 2-3mph quicker than it's actually traveling.
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vogz
Member
Vehicles use wheel or gear speed sensors to determine vehicle speed. Tesla offers multiple different wheel/tire packages on the Model 3 (as do all other manufacturers on their vehicles). The diameters of these setups are typically close enough that they change speedo calibration based on the wheel/tire package. That all said. Tires of the same size are not all created equally. They can have varying diameters and as they wear the diameter changes.
GPS on the other hand does't have to deal with any of these issues and is extremely accurate for determining speed. I didn't mention this before because I had forgotten I'd done it, but I've also used my Dragy unit (GPS + accelerometer) to measure drag racing runs and steady state speed and it showed the same 2-3mph as the phone GPS AND Police RADAR.
rpo
Member
How about FSD trying to use the center turn lane to pass vehicles throughout my entire city? I think that qualifies as dumb...especially considering the FSD animation correctly shows it is a turn lane with turn arrows and solid/dotted lines on each side of the center lane. It's mindboggling how terrible it is.
I just assumed how speed is measured was regulated by a Federal agency, since most things in a car are regulated. AND, that the speedometer must never underreport the speed, it always has to overreport the speed for safety reasons. I'm pretty sure that's required.
Like most things the regulations will lag behind technology improvements. ABRP as one of their features in calculating trips and trip times, will calculate your actual speed via GPS, then let you know how much over reporting your car is doing. Mine is 3 to 4% over, so when I'm doing about 50mph, I know I'm actually doing 48mph. It makes it perfect for me, knowing that I'm actually doing 8mph over the speed limit, rather than 10mph. Fewer cops are alerted.
From the summer, thus the high efficiency, 225Wh/mi@65mph. I swapped out my tires in the Fall for a new set.
Like most things the regulations will lag behind technology improvements. ABRP as one of their features in calculating trips and trip times, will calculate your actual speed via GPS, then let you know how much over reporting your car is doing. Mine is 3 to 4% over, so when I'm doing about 50mph, I know I'm actually doing 48mph. It makes it perfect for me, knowing that I'm actually doing 8mph over the speed limit, rather than 10mph. Fewer cops are alerted.
From the summer, thus the high efficiency, 225Wh/mi@65mph. I swapped out my tires in the Fall for a new set.
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Im pretty close to just amending the thread title with [everything on autopilot / FSD] and moving it to the autopilot subforum,lol.
Speed signs are not 'Police radar'. They're not calibrated by the cops. They're calibrated by the manufacturer. It's highly doubtful that a cop could use a speed sign to write you a ticket. In contrast, they're required to calibrate their radar guns before each use. While it's compelling that you're getting several sources that agree with the Tesla being the lone outlier. 2-3 MPH variation is virtually nothing.
vogz
Member
They are Radar system that are owned by the Police department. (I'm talking about the trailer mounted signs that police departments move around to different high traffic areas). I never said they were calibrated by the department, but they are obviously calibrated by the manufacturer and have far less variables affecting their accuracy (when one vehicle is driving head on and not yet at a more aggressive angle that can reduce reading.) vs. a passenger car's speedometer where something as simple as worn tires can change the readout in the vehicle.
But all of that is irrelevant, as I'm comparing the speed reading to other measuring devices such as my phone and Dragy (which is literally designed to accurately measure vehicle speed).
4-6% speedo error may be "virtually nothing" to you, but that's the most significant speedometer error that I've seen in a modern vehicle and that means that for every 10,000 miles I drive, my car is recording an additional 400-600 miles. That's far from "nothing".
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This article says most cars have a variation of +- 2.5 MPH.
Understanding Discrepancies in Radar-Captured Driver Speeds
The speeds revealed by driver feedback signs and other speed capturing devices are sometimes different than those reported by a car's speedometer. Why?
www.radarsign.com
