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Stealhead · 07-07-12, 02:56 AM

Well my speedo in my newer vehicle must be fairly close then because I have been ticketed 3 times and each time I was 100% aware of my speed and I do not give the law any information as to my exact speed but they will tell you and they have each time hit my speed on the head as to what the speedo was claiming.Maybe some cops a very good a math I recon.I have a old 240Z and that things speedo is off by almost 20MPH I know that because if I where actually going the speed it points at down my dirt road my head would smashing into the ceiling.

According to what I read your speedo can be 10% fast in the US but not any percentage off below actual speed.I also read that GPS in theroy is only off by 1% however that measurement is not constant it is over a length of time(very short but still it will miss changes) so it is not always 100% accurate either.If you have the cruise set and are on a level road then the GPS is more accurate.If you in conditions with a lot of speed variation then your speedo is more reliable.

Of course once I got pulled over in a 91 Honda Civic I had it nearly pegged which is 105MPH and I got pulled over and the cop said that I was going 77 MPH and I said "Sir you are correct I was going about 77MPH" he only gave me a warning this was in a 55 zone.Even if the speedo was 10% fast in that case I was still going about 95 MPH.I think he was just impressed that I had the pelotas to go that fast.

I would lean with a newer vehicle with the factory desgin tire and wheel size your speedo is likely not 10% fast but closer to 4 or 5 % fast.

Another thing to consider the GPS uses very accurate math (but the measurements can be incorrect because of spotty signal) most GPS have a fastest speed traveled a freind of mine looked at his once (this was the built into the dash kind) on his Prius and it said 180MPH yeah not possible I also read on a GPS forum once a page that listed top speeds traveled and one guy posted a picture of his 500mph.So the best bet is to use both your speedo and your GPS to be sure.

07-07-12, 02:56 AM	#15
Stealhead Navy Seal Join Date: Feb 2009 Location: Kentucky Posts: 5,421 Downloads: 85 Uploads: 0	Well my speedo in my newer vehicle must be fairly close then because I have been ticketed 3 times and each time I was 100% aware of my speed and I do not give the law any information as to my exact speed but they will tell you and they have each time hit my speed on the head as to what the speedo was claiming.Maybe some cops a very good a math I recon.I have a old 240Z and that things speedo is off by almost 20MPH I know that because if I where actually going the speed it points at down my dirt road my head would smashing into the ceiling. According to what I read your speedo can be 10% fast in the US but not any percentage off below actual speed.I also read that GPS in theroy is only off by 1% however that measurement is not constant it is over a length of time(very short but still it will miss changes) so it is not always 100% accurate either.If you have the cruise set and are on a level road then the GPS is more accurate.If you in conditions with a lot of speed variation then your speedo is more reliable. Of course once I got pulled over in a 91 Honda Civic I had it nearly pegged which is 105MPH and I got pulled over and the cop said that I was going 77 MPH and I said "Sir you are correct I was going about 77MPH" he only gave me a warning this was in a 55 zone.Even if the speedo was 10% fast in that case I was still going about 95 MPH.I think he was just impressed that I had the pelotas to go that fast. I would lean with a newer vehicle with the factory desgin tire and wheel size your speedo is likely not 10% fast but closer to 4 or 5 % fast. Another thing to consider the GPS uses very accurate math (but the measurements can be incorrect because of spotty signal) most GPS have a fastest speed traveled a freind of mine looked at his once (this was the built into the dash kind) on his Prius and it said 180MPH yeah not possible I also read on a GPS forum once a page that listed top speeds traveled and one guy posted a picture of his 500mph.So the best bet is to use both your speedo and your GPS to be sure. Last edited by Stealhead; 07-07-12 at 03:20 AM.