Speedometer accuracy?
#1
Driver School Candidate
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Join Date: Aug 2013
Location: TX
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Speedometer accuracy?
Hi all,
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
#5
Hi all,
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
My ES300h has standard 17" Michelin tires. And, I have a professional quality Race Logic "Performance Box" GPS that is used as test gear. It updates at rate of 10 times per second and reads out to two decimal places. Tires set at 36 PSI (cold), I drove over 700 miles, at 60 to 80 mph, in the gently rolling roads of west Texas. On a couple of shorter checks, it gave the same relative results. First, my odometer actually read less than the GPS distance value (which reads in feet, by the way, or 5,280 per mi.), which is unusual. In fact, it reads 2.5% low. So, that would affect the speedometer reading, as a relative value. With that known error, my speedometer reads right on from 65 mph to 80 mph. At 40 to 60 mph, it reads about one-quarter mph high and about one mph high at 30, for some reason. Your results, as the saying goes, will vary.
#6
Some variances are acceptable under federal guidelines.
Start changing the diameter of the tire/wheel combinations and
The results can be much more.
http://www.foxnews.com/leisure/2012/...-speedometers/
John
Start changing the diameter of the tire/wheel combinations and
The results can be much more.
http://www.foxnews.com/leisure/2012/...-speedometers/
John
#7
I have a Scan Gauge which is very accurate (radar checked). The difference in true speed to reported speed varies from 1-3 mph depending on the speed. For example, at 28mph the difference is 1 mph (speedometer shows 28, actual speed is 27) while at 65mph the difference is 3 mph (speedometer shows 65 while the actual speed is 62).
A couple of interesting notes about the speedometer. If you are driving at a constant speed with the cruise control on while on a level road and reset the average speed display, the true vehicle speed will be shown. I have the Radar Cruise Control and the digital display speed is off slightly compared to both the speedometer and Scan Gauge. The car's computer knows exactly how fast the car is going. The average speed reported is typically identical to the Scan Gauge speed.
For some reason, Toyota consistently has their speedometers showing slightly higher than true speed.
A couple of interesting notes about the speedometer. If you are driving at a constant speed with the cruise control on while on a level road and reset the average speed display, the true vehicle speed will be shown. I have the Radar Cruise Control and the digital display speed is off slightly compared to both the speedometer and Scan Gauge. The car's computer knows exactly how fast the car is going. The average speed reported is typically identical to the Scan Gauge speed.
For some reason, Toyota consistently has their speedometers showing slightly higher than true speed.
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#8
I have a Scan Gauge which is very accurate (radar checked). The difference in true speed to reported speed varies from 1-3 mph depending on the speed. For example, at 28mph the difference is 1 mph (speedometer shows 28, actual speed is 27) while at 65mph the difference is 3 mph (speedometer shows 65 while the actual speed is 62).
A couple of interesting notes about the speedometer. If you are driving at a constant speed with the cruise control on while on a level road and reset the average speed display, the true vehicle speed will be shown. I have the Radar Cruise Control and the digital display speed is off slightly compared to both the speedometer and Scan Gauge. The car's computer knows exactly how fast the car is going. The average speed reported is typically identical to the Scan Gauge speed.
For some reason, Toyota consistently has their speedometers showing slightly higher than true speed.
A couple of interesting notes about the speedometer. If you are driving at a constant speed with the cruise control on while on a level road and reset the average speed display, the true vehicle speed will be shown. I have the Radar Cruise Control and the digital display speed is off slightly compared to both the speedometer and Scan Gauge. The car's computer knows exactly how fast the car is going. The average speed reported is typically identical to the Scan Gauge speed.
For some reason, Toyota consistently has their speedometers showing slightly higher than true speed.
#9
Hi all,
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
I took my phone GPS and checked the speed and it was consistently 2 miles below what my car speedometer showed (i.e. 63 mph when the needle was at 65). The phone GPS seems to match the speed in my 2004 Honda Accord and 2008 Chrysler Town and Country spot on. Have any of you tested the speedometer? I wonder if there is a way to better calibrate it. I have the 18" wheel package, but didn't think that made a difference.
Interestingly, when I had a 2013 Toyota Avalon rental a couple of months ago I played with the digital speed display in the car (the digital speed is a display option in that car). I observed then that the analog speedometer and digital speedometer didn't quite match. I recognized I had to put the needle on the analog a bit over the number to get the desired speed on the digital display. Now I'm thinking that the "a bit over" amount was 2 mph, the discrepency I'm seeing between my ES and the phone GPS.
Any thoughts?
Jacob
Mine looks like it is 1 to 2 mph over until I lean forward. Just the angle of the speedometer that is causing the off reading. I know this because when my radar cruise control set at 60 mph, my speedometer looks like 61/62 mph until I lean forward and then it is magically 60 mph.
#11
Lexus Fanatic
Every Toyota/Lexus product I have owned (6) has had a speedometer that reads 2MPH fast.
#12
Since the 1970's Toyota speedometers have been calibrated to read 2 MPH faster than actual vehicle speed. One obvious unintended consequence is that you'll get a few less speeding tickets over the life of the vehicle.
#13
Lexus Fanatic
Yep, I have to remember when I'm driving the Jeep that the speedometer is dead on accurate LOL. Cruise set to 80 on the highway in the Lexus is 13 over. In the Jeep its 15 over...15 over is apparently a bigger deal...trust me
#14
"but the Scan Gauge has no inherent ability to display accurate speed"
While this may be true, I have owned this scan gauge for several years, have used it 4 Toyota products (2 Lexus), and have had the opportunity to check it numerous times over the years against local radar, it has consistently been accurate. And it corresponds precisely to the built-in "Average Speed" menu item as per my description above. And as also noted above, Toyota speedometers are 'know' to be inaccurate by about 2 mph.
The bottom line is the car knows how fast it is going and is quite accurate in determining its speed (on a stock vehicle).
While this may be true, I have owned this scan gauge for several years, have used it 4 Toyota products (2 Lexus), and have had the opportunity to check it numerous times over the years against local radar, it has consistently been accurate. And it corresponds precisely to the built-in "Average Speed" menu item as per my description above. And as also noted above, Toyota speedometers are 'know' to be inaccurate by about 2 mph.
The bottom line is the car knows how fast it is going and is quite accurate in determining its speed (on a stock vehicle).
Last edited by ElliotB; 09-08-13 at 08:54 AM.
#15
"but the Scan Gauge has no inherent ability to display accurate speed"
While this may be true, I have owned this scan gauge for several years, have used it 4 Toyota products (2 Lexus), and have had the opportunity to check it numerous times over the years against local radar, it has consistently been accurate. And it corresponds precisely to the built-in "Average Speed" menu item as per my description above. And as also noted above, Toyotas speedometers are 'know' to be inaccurate by about 2 mph.
The bottom line is the car knows how fast it is going and is quite accurate in determining its speed (on a stock vehicle).
While this may be true, I have owned this scan gauge for several years, have used it 4 Toyota products (2 Lexus), and have had the opportunity to check it numerous times over the years against local radar, it has consistently been accurate. And it corresponds precisely to the built-in "Average Speed" menu item as per my description above. And as also noted above, Toyotas speedometers are 'know' to be inaccurate by about 2 mph.
The bottom line is the car knows how fast it is going and is quite accurate in determining its speed (on a stock vehicle).