XD's Speedometer vs Public safety meter
Thread Starter
Member
Joined: Jul 2009
Posts: 35
From: LA
XD's Speedometer vs Public safety meter
Recently local city decided to put up those mobile machines that tells you what is the speed you're currently driving at on one of the streets here, hope to get you to stay within limit.
I have driven past these two machines about 4 times so far (one at each end of street for each direction). What I noticed was, those machine's reported speed is about ~5 MPH HIGHER than my XD's speedometer reported speed. At first, I couldn't believe it. But after a few times, I can confirm that indeed, when I was driving at 30MPH as reported by my XD's speedometer, the safety machine was flashing a "You're driving at 35 MPH!!!" (the speed limit there is 35 MPH).
When I did those tests, there was no other car behind me, they were at least 3 blocks away. I checked to make sure there is no other car traveling in same direction as me. I even did this after midnight, when hardly any car was on the road at all, except my car.
But...I also drive a 92 Honda Accord, and I check its speed against the public safety meter....the interesting thing is, my Accord's Speedometer is 4-5 mph LESS than what the street machine was reporting, i.e. when my Accord's Speedometer tells me I am driving at 38 mph, the street machine is telling me I am driving at 33-34 mph. I can confirm that on at least 2 occasion already with my Accord.
It's good for now these so-called public safety speed reporting machine can't give out tickets automatically, otherwise I'd be ____ed because whatever speed it's reporting isn't the same as what my car is telling me, different cars get different result.
I have driven past these two machines about 4 times so far (one at each end of street for each direction). What I noticed was, those machine's reported speed is about ~5 MPH HIGHER than my XD's speedometer reported speed. At first, I couldn't believe it. But after a few times, I can confirm that indeed, when I was driving at 30MPH as reported by my XD's speedometer, the safety machine was flashing a "You're driving at 35 MPH!!!" (the speed limit there is 35 MPH).
When I did those tests, there was no other car behind me, they were at least 3 blocks away. I checked to make sure there is no other car traveling in same direction as me. I even did this after midnight, when hardly any car was on the road at all, except my car.
But...I also drive a 92 Honda Accord, and I check its speed against the public safety meter....the interesting thing is, my Accord's Speedometer is 4-5 mph LESS than what the street machine was reporting, i.e. when my Accord's Speedometer tells me I am driving at 38 mph, the street machine is telling me I am driving at 33-34 mph. I can confirm that on at least 2 occasion already with my Accord.
It's good for now these so-called public safety speed reporting machine can't give out tickets automatically, otherwise I'd be ____ed because whatever speed it's reporting isn't the same as what my car is telling me, different cars get different result.
Senior Member
SL Member
Joined: Sep 2008
Posts: 1,265
From: Cranberry Township, PA
Recently local city decided to put up those mobile machines that tells you what is the speed you're currently driving at on one of the streets here, hope to get you to stay within limit.
I have driven past these two machines about 4 times so far (one at each end of street for each direction). What I noticed was, those machine's reported speed is about ~5 MPH HIGHER than my XD's speedometer reported speed. At first, I couldn't believe it. But after a few times, I can confirm that indeed, when I was driving at 30MPH as reported by my XD's speedometer, the safety machine was flashing a "You're driving at 35 MPH!!!" (the speed limit there is 35 MPH).
When I did those tests, there was no other car behind me, they were at least 3 blocks away. I checked to make sure there is no other car traveling in same direction as me. I even did this after midnight, when hardly any car was on the road at all, except my car.
But...I also drive a 92 Honda Accord, and I check its speed against the public safety meter....the interesting thing is, my Accord's Speedometer is 4-5 mph LESS than what the street machine was reporting, i.e. when my Accord's Speedometer tells me I am driving at 38 mph, the street machine is telling me I am driving at 33-34 mph. I can confirm that on at least 2 occasion already with my Accord.
It's good for now these so-called public safety speed reporting machine can't give out tickets automatically, otherwise I'd be ____ed because whatever speed it's reporting isn't the same as what my car is telling me, different cars get different result.
I have driven past these two machines about 4 times so far (one at each end of street for each direction). What I noticed was, those machine's reported speed is about ~5 MPH HIGHER than my XD's speedometer reported speed. At first, I couldn't believe it. But after a few times, I can confirm that indeed, when I was driving at 30MPH as reported by my XD's speedometer, the safety machine was flashing a "You're driving at 35 MPH!!!" (the speed limit there is 35 MPH).
When I did those tests, there was no other car behind me, they were at least 3 blocks away. I checked to make sure there is no other car traveling in same direction as me. I even did this after midnight, when hardly any car was on the road at all, except my car.
But...I also drive a 92 Honda Accord, and I check its speed against the public safety meter....the interesting thing is, my Accord's Speedometer is 4-5 mph LESS than what the street machine was reporting, i.e. when my Accord's Speedometer tells me I am driving at 38 mph, the street machine is telling me I am driving at 33-34 mph. I can confirm that on at least 2 occasion already with my Accord.
It's good for now these so-called public safety speed reporting machine can't give out tickets automatically, otherwise I'd be ____ed because whatever speed it's reporting isn't the same as what my car is telling me, different cars get different result.
every one that i pass on the interstates when i have cruise set say one MPH less than what i have it set for.
Senior Member
SL Member
Joined: Jul 2008
Posts: 273
From: Portland, Oregon
There are some unasked questions here...
1. Is your ride on Stock tires and wheels?
2. If no what size tire and wheels are you using?
3. I would be willing to bet those machines are not reading a static speed. They may be able to read higher/lower than actual speeds.
1. Is your ride on Stock tires and wheels?
2. If no what size tire and wheels are you using?
3. I would be willing to bet those machines are not reading a static speed. They may be able to read higher/lower than actual speeds.
Senior Member
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Joined: Nov 2008
Posts: 1,023
From: Annapolis, MD
Most radar devices read correctly when they are dead-on to the vehicle. The more off-angle it is, the lower the reading will be. Also, since they are not used for enforcement, they don't need to be calibrated regularly.
Thread Starter
Member
Joined: Jul 2009
Posts: 35
From: LA
My month old XD has not been modified at all, not even a sticker. Everything is the same as the day it came off the car lot.
Yeah, I doubt they are calibrated correctly if at all. In this economy I doubt they hired an engineer to do careful test before they rolled these machines out.
I do wish there are other machines in other streets to see what speed I'd get, but haven't found any near me yet.
Yeah, I doubt they are calibrated correctly if at all. In this economy I doubt they hired an engineer to do careful test before they rolled these machines out.
I do wish there are other machines in other streets to see what speed I'd get, but haven't found any near me yet.
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