Just curious - if anybody else has found that the speedometer in the a3 over-reports by about +2 to +3.5 over your actual speed?

I noticed it on a road trip while comparing speeds on my Garmin Nuvi and the dash a week ago & thought I'd grab a pilot friends Garmin 496 GPS and compare. Well my little Garmin GPS reads { suprisingly } the same as 496 GPS on our ground speed - albeit it's doing so at a much slower sample rate.

So we had both units on the dash - and put the car out on a long straight, flat & non-congested stretch of road and with cruise control holding steady - compared the differences at various speeds.

I we pretty much found that on average the car's speedo over-reports by about +2.65 mph average at any given speed over 35 mph.

Has anyone else noticed this?


2008 2.0t / S_line / Stock Rims & Tyres

I actually noticed the same i just drove from tampa to boston and when my cruise control was set at 80 on the speed-o it showed that i was only going 77/78 on the digital screen n the cluster. Pretty wierd.

Yeah, mine reads about 3mph over at highway speeds as well. At least they're consistent about this f^ck up. LOL




Cheers!

Same for me....Speedo is optimistic by about 3-5km/h.

I'll venture to say that every German car sold in North America, regardless of manufacturer, is overoptimistic about how fast the car is moving.

So since it looks to be getting unanimous on this does this mean that if we put on 235/45's on our stock rims we will be closer to the actual speed the spedo is staying?

I once heard that there's a German law that speedometers must never under-report speed, so they all tend to over-report slightly, as shipo suggests. Mine seems to be 2-3mph slow at 70mph, but that is probably true for most of the cars I've owned over many years. If we didn't have inexpensive GPS these days, we wouldn't worry about it!

Yea I noticed it mine was off about 2-3 MPH when I drove by those things that tell you your going too fast.

A bit of reading for you folks:

http://en.wikipedia.org/wiki/Speedometer#International_agreements

And for those who don't like to read... long story short: it's normal.

That's an interesting bit of reading - I like the disclaimer about gps versus in-car reporting. There's some good truth in there - as well as a lot of allowable variance too - it's also why I was specific about using a flight rated GPS versus my little cheap nuvi consumer unit. { the GPS496 updates at 5hz, which is a lot faster than the Nuvi does. } And we were pretty methodical about the road and distance we tested it on. { straight, flat & abandoned transient / ambient temp approx 82 degrees & the car had been driven so the tyres were warmed up }

I'd expect that a variance of 1-2 mph due to tyre wear / inflation / ambient temperature expansion etc. But 3+ at various temps seems a bit much - I've noticed it in the summer too where mechanicals would be fully expanded { larger rim/tyre/gearing circumference }

bla bla bla... getting waylaid in technicals - can this be fixed/adjusted/corrected?

good. i drive too fast as is.

ORIGINAL: trentune_f

I'd expect that a variance of 1-2 mph due to tyre wear / inflation / ambient temperature expansion etc. But 3+ at various temps seems a bit much - I've noticed it in the summer too where mechanicals would be fully expanded { larger rim/tyre/gearing circumference }

bla bla bla... getting waylaid in technicals - can this be fixed/adjusted/corrected?

3+ is still within the acceptable norm (at least for UK, where I assume you are located). Why would you "fix" it? Does it bother you THAT much?

i concur on that.. i've been using an hp pocket pc gps on our previous 99 passat 1.8t, our current passat glx and 07 a3- and
all are optimistic of 2-3mph speed rating. I dont mind at all..used to it..
I recently downloaded a program for my PocketPC GPS (wm5/ travel companion) called GPS Performance... using your existing GPS, and windows mobile 5, it can measure 0-30,40,60, 100 etc.. measures 1/4 mile runs, and also approximate acceleration Gs.
It can also record a track and it will plot automatically for your lap times.. Registered version is $34.95, but you can download a free trial version (which does not save your runs, and also less features)
My first trial (i havent gone to a 'secure/safe' place to do these runs..but tried it on an emptly boulevard- 1) 7.00s, 2)6.5 3)6.8,
average was 6.8 - STOCK and i wasnt really pushing the car since i was doing it on public streets..

e

ORIGINAL: cuski

ORIGINAL: trentune_f

I'd expect that a variance of 1-2 mph due to tyre wear / inflation / ambient temperature expansion etc. But 3+ at various temps seems a bit much - I've noticed it in the summer too where mechanicals would be fully expanded { larger rim/tyre/gearing circumference }

bla bla bla... getting waylaid in technicals - can this be fixed/adjusted/corrected?

3+ is still within the acceptable norm (at least for UK, where I assume you are located). Why would you "fix" it? Does it bother you THAT much?



Cuski - From London but relocated to New York.

No it dosen't really bother me that much... it's just one of those things that since we have the option to display our speed in digital format / I'd assumed it was more accurate than a visual reading of a needle speedometer.