PeteyPye
Member
I regularly see myself doing 70mph in my Grande Punto 1.9 (according to my needle) but my TomTom argues the toss and says I'm doing 64mph...
What's yours reading, in what car?
What's yours reading, in what car?
How Accurate is Your Speedo?
- Thread starter PeteyPye
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How Accurate is Your Speedo?
My Fiesta at 70mph on the needle, shows 64 on the sat nav... however, when i unlock my speedo and get the digital speed reading, it corresponsd to the sat nav perfectly.
when going through 50mph average cameras, i use my sat nav doing about 49mph, my speedo says around 53mph 
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PeteyPye
Member
Only car speedo's or women's speedo's please.
the Sei - when the speedo said i was doing 40 - i was nearer 33mph
the focus seems exact
the focus seems exact
your difference is very much the norm. GPS reading 65mpg when speedo says 70mph is true on almost every car i have tested (and thats literally a couple of dozen cars).
i have noticed some newer cars (passat & 308) are more accurate, which isnt a good thing. if you stick bigger wheels on you could then get into a situation where it reads slower than you're actually going.
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PeteyPye
Member
FAIL
I will quite happily sit at 30mph (according to needle) going past a speed camera but I am constantly given funny looks, probably because in reality I am doing 24mph or something... I knew there was a speed difference but I always seem to crawl through cameras when everyone else goes through quite quickly.
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lol i tested this on my mates scooter, can anyone guess what the sat nav read when the scooter read 50mph? (50cc racing type ped)
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PeteyPye
Member
36mph?
SeicentoS
Established member
In the starlet GT doing 70 on the clock, GPS said 69, in the clio doing 70 on the clock, GPS says 67.
33 lol!
1997 Marea 20v, on the motorway with the needle reading 70mph the sat nav reading is 67mph. I think thats pretty good accuracy. In town with the needle on 30 the sat nav will read 27mph, I expected the accuracy to get worse as you got faster but it's still 3mph.
It does depend on whether the road is straight and level, going up or down hill causes fluctuations in the reading of upto +2mph so at 70mph needle reading, the sat nav could read 65mph if the road is going up or downhill.
It does depend on whether the road is straight and level, going up or down hill causes fluctuations in the reading of upto +2mph so at 70mph needle reading, the sat nav could read 65mph if the road is going up or downhill.
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I find my Cinq under reads the speed by about 5MPH
i failed
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i failed
This seems to be happening more and more frequently...
In my bus I have an electronic tacho, a speedo and, sometimes, I use my satnav.
The bus has a speed limiter fitted to prevent speeds over 60mph. There have been occasions when I have had the tacho reading 112kph, the dash showing 65mph & the satnav showing 62 - OK, it is a long downhill stretch of dual carriageway so I have gravity on my side but there really shouldn't be such a discrepancy.
I figure the tacho is the most accurate as it has to be frequently calibrated. The satnav doesn't update its position often enough for it to provide accurate speed readings.
As an interesting diversion. I often see threads popping up asking if it's possible to use larger wheels & people advocating wheels up to a couple of inches bigger than existing - the wheels may just fit under the arches but what about the impact larger diameter wheels will have on the accuracy of the speedo? (not to mention the way the car will handle & power transfer from the engine to the wheels).
The bus has a speed limiter fitted to prevent speeds over 60mph. There have been occasions when I have had the tacho reading 112kph, the dash showing 65mph & the satnav showing 62 - OK, it is a long downhill stretch of dual carriageway so I have gravity on my side but there really shouldn't be such a discrepancy.
I figure the tacho is the most accurate as it has to be frequently calibrated. The satnav doesn't update its position often enough for it to provide accurate speed readings.
As an interesting diversion. I often see threads popping up asking if it's possible to use larger wheels & people advocating wheels up to a couple of inches bigger than existing - the wheels may just fit under the arches but what about the impact larger diameter wheels will have on the accuracy of the speedo? (not to mention the way the car will handle & power transfer from the engine to the wheels).
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you try having 30+ tabs open at once.
I find nearly all cars do this, must be a built in deliberate error to stop you getting caught speeding or something? you will find your sat nav matches up perfectly with those digital readout things with the smiley/frowny faces at the side of the road so it must be the speedo thats out. never though of checking my scooter with sat nav!!
