Speedometer accuracy
#1
Speedometer accuracy
I put my Garmin GPS in WAAS mode and did some speed testing to see how accurate the speedo is.
It looks like the speedo is 2mph optimistic. So a steady indicated 70 mph on the speedo is actually 68mph.. pretty accurate. So now I know I can go a bit faster in speed traps.
It looks like the speedo is 2mph optimistic. So a steady indicated 70 mph on the speedo is actually 68mph.. pretty accurate. So now I know I can go a bit faster in speed traps.
#2
I use Microsoft streets and trips 2006 for GPS and noticed a similar discrepancy. The speedo on the xB is off by 2 (no more than 3 though) miles an hour. Although, since the speed is determined by gps satellites and not by a guage on the car, there is also room for error.
- sh00k
- sh00k
#3
A GPS vs. Speedometer test on my 2005 xB on a lengthy near-straight segment of interstate highway (using an assistant to minimize driver distraction and using cruise control for speed maintenance) shows a similar 1.5 to 2 MPH difference at around 60mph. The speedometer seems to run a little bit high, which is just fine with me. Oh, and my wheels are the stock steelies - that's pretty important to note in this test.
Also, I can make a mileage accuracy adjustment of approximately -3% to my fuel economy figures, which adds about 0.9 mpg to the odometer/fuel usage calculation.
Also, I can make a mileage accuracy adjustment of approximately -3% to my fuel economy figures, which adds about 0.9 mpg to the odometer/fuel usage calculation.
#7
Wholeflaffer, who installed your cruise? And if I may ask, how much did it cost?
The unit I got is the same as the "factory" unit that the southeast port used, and is apparently meant for installation in the xB. It's made by Rostra, and there's an entertaining thread about it at https://www.scionlife.com/forums/viewtopic.php?t=102894.
#8
I also got the cruise control, port install.. It works.. but its slow to respond and varies up to 5 mph when in use.
Too bad the xB doesnt use a drive by wire system. It makes things much easier to implement and its much cheaper.
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable..
I'm sure Scion will eventually move to this sometime in the future... also makes for less of a mess under the hood... no cables or cruise module.
Too bad the xB doesnt use a drive by wire system. It makes things much easier to implement and its much cheaper.
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable..
I'm sure Scion will eventually move to this sometime in the future... also makes for less of a mess under the hood... no cables or cruise module.
#9
Originally Posted by mikem53
Too bad the xB doesnt use a drive by wire system. It makes things much easier to implement and its much cheaper.
...
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable.
...
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable.
#10
Originally Posted by wholeflaffer
Originally Posted by mikem53
Too bad the xB doesnt use a drive by wire system. It makes things much easier to implement and its much cheaper.
...
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable.
...
I have drive by wire in all my other cars.. It makes the cruise control work seamlessly. It functions smooth and accurately and is less complex and more reliable.
#11
Originally Posted by mikem53
good point.. Stock wheels and tires on my test also..
#13
Does the cruise you had installed take the pedal away as it adjusts the gas? My tC didn't and that was a little disturbing after my Golf which let me know exactly how far down the pedal was.
Sorry to turn this into a cruise thread, I promise to post my observations on the speedometer when I mess with it this weekend!
Sorry to turn this into a cruise thread, I promise to post my observations on the speedometer when I mess with it this weekend!
#14
Originally Posted by guitarsurf
Does the cruise you had installed take the pedal away as it adjusts the gas?
I should think that "drive by wire" cars might not be able to do this unless some sort of servo-motor is attached to the pedal for feedback.
#15
I have noticed that MY speedo is reading LESS than what my GPS is reading. It is off 5 miles per 100 miles driven (distance, not speed). This figure really helped with explain a low MPG problem I was having (well, it didn't help with it, but it made the numbers look better). This was done over a 2 week 5000 mile trip and the GPS is dead on with the mile markers AND mapquest figures....so I would like to say the GPS is pretty accurate.
Just my $.02
BTW...I am running 17" and my tires are within 1/2" of stock height (stock is like 23.7, mine are 24.2)
Just my $.02
BTW...I am running 17" and my tires are within 1/2" of stock height (stock is like 23.7, mine are 24.2)
#16
Originally Posted by x_rayted711
I have noticed that MY speedo is reading LESS than what my GPS is reading. It is off 5 miles per 100 miles driven (distance, not speed). This figure really helped with explain a low MPG problem I was having ....so I would like to say the GPS is pretty accurate.
...
BTW...I am running 17" and my tires are within 1/2" of stock height (stock is like 23.7, mine are 24.2)
...
BTW...I am running 17" and my tires are within 1/2" of stock height (stock is like 23.7, mine are 24.2)
Bring a GPS and ask the dealer rep to take a quick ride on the nearest highway...show how different the speedometer reads compared to the GPS in his or her hand.
You may want to ask your salesperson to do this ride with you...Unlike a service tech who must account for every minute, the sales rep will usually be able to take a few minutes to keep (or make) an existing customer happy. If the speed difference is objectionable, he or she would likely be on your side in dealing with the service department.
#17
Originally Posted by HeathenBrewing
Originally Posted by mikem53
good point.. Stock wheels and tires on my test also..
Its not hard to re-calibrate the speedo for the tires being used.