Speedometer - AudiWorld Forums

Go Back   AudiWorld Forums > Audi Models > Audi A6 / S6 / RS 6 > A6 (C7 Platform) Discussion
Sign in using an external account
Register Forgot Password?


A6 (C7 Platform) Discussion Discussion forum for the C7 Audi A6 produced from 2011

Speedometer

Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
Old 05-25-2014, 09:14 AM   #1
Audiworld Junior Member
 
Join Date: Apr 2014
Posts: 67
Default Speedometer

Why is my speedometer off by two or three miles higher?
My radar detector in my other three cars is spot on but in the Audi A6 is is off. Very annoying.
537playing is online now   Reply With Quote
Old 05-25-2014, 09:57 AM   #2
AudiWorld Member
 
Join Date: Dec 2013
Location: Ontario, Canada
Posts: 225
Default

don't lose your hair over it. this is normal.
Superfly_A6 is offline   Reply With Quote
Old 05-25-2014, 03:46 PM   #3
AudiWorld Member
 
Join Date: Jul 2011
Posts: 428
Default

All German cars I owned in the past are like that. They purposely set the speedometer 2 to 3 miles higher so you are always under posted speed limit if you drive at the limit. In my old Merc I can press a few buttons on and it can show the real speed and a whole bunch of other technical info on HVAC display.
__________________

2012 A6 3.0T Prestige S-Line Sport Suspension Pirelli P-Zero 255/35/20

[Glacier White Metallic // Black Milano Leather // Matte Brushed Aluminium Inlay // Black Headliner]

[LED Headlights // Adaptive Cruise Control // Audi Pre Sense Plus // Audi Brake Guard // Audi Side Assist // Head Up Display // Night Vision // Shift Paddles]

[Bang & Olufsen Advanced Sound System // Electric Rear Sunshade // Manual Side Sunshade // Four Zone Climate Control // Heated and Ventilated Front Seats // Heated Rear Seats // LED Ambient Lighting Plus // Glass Sunroof]
qqq1970 is offline   Reply With Quote
Old 05-25-2014, 06:03 PM   #4
AudiWorld Super User
 
snagitseven's Avatar
 
Join Date: Jul 2001
Location: SE MA
Posts: 8,977
Default

Also, it's likely your computer MPG will read high as well. That one however, unlike the speedometer, can be adjusted with the VCDS (Vag-Com) cable and software.
__________________

- 2013 A6 3.0T Prestige, Quartz Gray/Black, 19" Sport, Driver Assist, LED headlights,Cold Weather and B&O;
Bridgestone RE970AS tires; XPel Ultimate full front, mirrors and rocker panels, Opti-coat Pro
- 2002 allroad 2.7t - 14y/55K mi and still like new
- 2009 A4 3.2 Prestige w/Nav (sold at 4y/48K mi)
- 2001 A6 2.7t (sold at 8y/98K mi)
snagitseven is offline   Reply With Quote
Old 05-25-2014, 09:54 PM   #5
AudiWorld Senior Member
 
DeerHunter's Avatar
 
Join Date: Nov 2012
Location: Edmonton, AB
Posts: 936
Default

Tangential question: Has anyone been able to use VAG-COM to enable GPS-derived speed in the Nav screen? Even the cheaperst Garmin has this capability and it would be a useful option for us optimistic German types.
__________________
2013 Glacier White S6
2005 S4 Cabriolet (Sold)
DeerHunter is online now   Reply With Quote
Old 05-26-2014, 04:03 AM   #6
AudiWorld Member
 
TJKs '02 2.7T's Avatar
 
Join Date: Sep 2004
Location: Family and Photography
Posts: 257
Default

I also noticed that my speedometer reads around 2-3 MPH below what my Waze App is reporting...probably better this way versus under reporting the speed. However, more annoying is the MPG errors...my '02 A6 was always off by at least 2 MPG and after my first reading on my new '13 A6 it came in again at 2 MPG over the actual.

The good part though is that I attained 25.8 MPG...better than I ever got on my prior Audi over 10 years...there have been times where it is shown on the "Short-Term" getting 34 MPG over a trip.
__________________
- 2013 A6 3.0T Prestige, Dakota Gray/Nougat, 19", Innovation Package, LED headlights, Cold Weather Package;
- 2002 2.7t - w/Nav, Sport Package, 6 Speed (sold at 10y/160K mi)
TJKs '02 2.7T is offline   Reply With Quote
Old 05-26-2014, 04:51 AM   #7
AudiWorld Super User
 
snagitseven's Avatar
 
Join Date: Jul 2001
Location: SE MA
Posts: 8,977
Default

Quote:
Originally Posted by TJKs '02 2.7T View Post
I also noticed that my speedometer reads around 2-3 MPH below what my Waze App is reporting...probably better this way versus under reporting the speed. However, more annoying is the MPG errors...my '02 A6 was always off by at least 2 MPG and after my first reading on my new '13 A6 it came in again at 2 MPG over the actual.

The good part though is that I attained 25.8 MPG...better than I ever got on my prior Audi over 10 years...there have been times where it is shown on the "Short-Term" getting 34 MPG over a trip.
As I mentioned a couple of posts ago, the DIS MPG consumption display can be adjusted to more closely match your real world calculation with VCDS:

Correct Consumption in DIS program
[17 - Instruments] [Adaptation - 10]
Look about 20 items down on the drop-down list for "Correct Consumption" and select it
Change 100 to xxx
Example - if your DIS is consistently off by 7% to your actual calculated mpg:
You RAISE the number to the percentage if DIS is OVER reporting mpg (i.e. 107)
You LOWER the number to the percentage if DIS is UNDER reporting mpg (i.e. 93)
__________________

- 2013 A6 3.0T Prestige, Quartz Gray/Black, 19" Sport, Driver Assist, LED headlights,Cold Weather and B&O;
Bridgestone RE970AS tires; XPel Ultimate full front, mirrors and rocker panels, Opti-coat Pro
- 2002 allroad 2.7t - 14y/55K mi and still like new
- 2009 A4 3.2 Prestige w/Nav (sold at 4y/48K mi)
- 2001 A6 2.7t (sold at 8y/98K mi)
snagitseven is offline   Reply With Quote
Old 05-26-2014, 04:55 AM   #8
AudiWorld Super User
 
snagitseven's Avatar
 
Join Date: Jul 2001
Location: SE MA
Posts: 8,977
Default

Quote:
Originally Posted by DeerHunter View Post
Tangential question: Has anyone been able to use VAG-COM to enable GPS-derived speed in the Nav screen? Even the cheaperst Garmin has this capability and it would be a useful option for us optimistic German types.
I've not seen any, probably because there's no MMI software code to support the feature.
__________________

- 2013 A6 3.0T Prestige, Quartz Gray/Black, 19" Sport, Driver Assist, LED headlights,Cold Weather and B&O;
Bridgestone RE970AS tires; XPel Ultimate full front, mirrors and rocker panels, Opti-coat Pro
- 2002 allroad 2.7t - 14y/55K mi and still like new
- 2009 A4 3.2 Prestige w/Nav (sold at 4y/48K mi)
- 2001 A6 2.7t (sold at 8y/98K mi)
snagitseven is offline   Reply With Quote
Old 05-26-2014, 07:27 AM   #9
AudiWorld Senior Member
 
twentysevenlitres's Avatar
 
Join Date: Aug 2006
Location: Melbourne, Victoria, Australia
Posts: 711
Default

Speedos reading over actual speed is a design rules thing.
In most countries speedos are allowed to have an error of 10% bit must not read under the stated speed.
Most manufacturers err on the side of caution and have to them read slightly over.

Also saves on any litigation issues ("but my speedo said I was doing 55 officer"!!).

Both my Audi's are a damn site more accurate than any of my GMH products in the past - 1-2% under vs 8% under - no wonder I'm always overtaking Falcons and Commodores on the freeway...

Excerpt from Australian Design Rules:
The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph*5.2.5. above, there shall be the following relationship between the speed displayed (V1 ) and the true speed (V2).
0 =< (V1 - V2) =< 0.1 V2 + 4 km/h
That's actually 10% + 4km/h, which is even further out (14% at 100km/h)

edit: bold = corrections of tense
__________________
Cheers,

Marty



Current:
2001 Audi S8
- Solar Sunroof, heated front and rear seats (just what you need in Australia!) Tinted side and rear glass, RNS-D, XCarLink, Bose, clunky old phone in arm rest!

Sold:
1997 Audi A4 Quattro - 5spd man "Hamilton's Club Sport" - will miss the old girl!

Last edited by twentysevenlitres; 05-26-2014 at 03:03 PM.
twentysevenlitres is offline   Reply With Quote
Old 05-26-2014, 09:00 AM   #10
AudiWorld Member
 
Join Date: Dec 2013
Posts: 280
Default

I think you may be reversing Speed reading with Odometer reading. Odometers are not permitted to read high. That is--they cannot indicate you have traveled 105miles when you only went 100 (that would reduce your warrantee for one thing). But the Speedometer reads a few mph higher than you are actually going. When I read 75mph, my GPS says I'm only doing 72. That keeps you from unintentionally speeding.
dicktahoe is offline   Reply With Quote
Old 05-26-2014, 09:15 AM   #11
AudiWorld Member
 
lnferno's Avatar
 
Join Date: Apr 2004
Posts: 509
Default

I think every Audi that I've owned, the speedo reads ~2 mph high
__________________
Present:
'13 Audi S6 Estoril Blue
Past:
'11 Audi A6 Avant 3.0T Suzuka Grey Prestige Stg II+
'06 Porsche Cayenne Turbo S
'01 Audi S4 - Stg III+
'06 Audi A4 Avant 2.0T Stg I
'06 Audi A4 2.0T - APR K04
'01 Audi S4 - Stg II
lnferno is offline   Reply With Quote
Old 05-26-2014, 11:58 AM   #12
AudiWorld Super User
 
snagitseven's Avatar
 
Join Date: Jul 2001
Location: SE MA
Posts: 8,977
Default

Also, consider that tire circumference will also affect the speedo and odometer. Even tires spec'd the same size by different brands will have slight variations in circumference. The you have some differences as the tread wears down; as a result, even if the speedo or odometer could be changed, there would be no way over time to maintain precise accuracy.
__________________

- 2013 A6 3.0T Prestige, Quartz Gray/Black, 19" Sport, Driver Assist, LED headlights,Cold Weather and B&O;
Bridgestone RE970AS tires; XPel Ultimate full front, mirrors and rocker panels, Opti-coat Pro
- 2002 allroad 2.7t - 14y/55K mi and still like new
- 2009 A4 3.2 Prestige w/Nav (sold at 4y/48K mi)
- 2001 A6 2.7t (sold at 8y/98K mi)
snagitseven is offline   Reply With Quote
Old 05-26-2014, 12:38 PM   #13
AudiWorld Member
 
Join Date: Dec 2013
Posts: 280
Default

And as the tire wears down, and the circumference gets smaller so the MPH reading will get worse (if it reads 75 when your doing 72, you'll now be only doing about 70.5 when it reads 75) and the Odometer error will decrease (if you're now traveling 105 miles when it indicates 100, with worn tires you'll only travel about 102 miles).
dicktahoe is offline   Reply With Quote
Old 05-27-2014, 07:40 AM   #14
AudiWorld Senior Member
 
feralc's Avatar
 
Join Date: Jun 2012
Location: CA
Posts: 1,139
Default

The yokohamas that came with my A7 are 27.4'' in diameter, the full tread depth is 10/32"
So between a new tire and a completely bald tire you will lose 20/32" in diameter
That is 2.28% difference between a brand new and a completely bald tire
This is an extreme example because you don't usually go that far before replacing the tire.
So if the speedometer is reading correctly and the speed is 65mph you will be traveling at around 63.5mph, not a big difference because as I said you usually replace the tire before.
__________________
FERRARI 360 SPIDER F1 2003
COBRA 1965
DUCATI DIAVEL 2011 CARBON RED
GRAND CHEROKEE ALTITUDE 2015


GONE (BUT NOT FORGOTTEN)
-AUDI A7 PRESTIGE 2012 GIAC STAGE 2 (460HP AND 420 FT-LBS), AWE TOURING DIAMOND BLACK EXHAUST, INJEN INTAKE, EIBACH SPRINGS, MOONLIGHT BLUE/VELVET BEIGE, FULL LEDS, SIDE ASSIST, 20" WHEELS, VAG-COM MODS.
-PORSCHE CAYENNE TURBO 2004
-HARLEY DAVIDSON NIGHT ROD SPECIAL 2009
-MERCEDES BENZ SL55 2003 527BHP, 557FT-LBS NO SPEED LIMITER.
-PORSCHE 911 CARRERA 4 2000 MILLENIUM EDITION
-BMW 325CI F1 CABRIO 2003
feralc is offline   Reply With Quote
Old 05-27-2014, 11:48 AM   #15
AudiWorld Member
 
Join Date: Dec 2013
Posts: 280
Default

"So if the speedometer is reading correctly and the speed is 65mph you will be traveling at around 63.5mph, not a big difference because as I said you usually replace the tire before."

Your calculations are the same as mine--reduce the actual speed you are traveling by about 1.5MPH. I just started already being 3MPH slow at 75MPH indicated as is the case with my A6
dicktahoe is offline   Reply With Quote
Old 05-27-2014, 03:30 PM   #16
AudiWorld Senior Member
 
twentysevenlitres's Avatar
 
Join Date: Aug 2006
Location: Melbourne, Victoria, Australia
Posts: 711
Default

You need to realise that tyres don't run round - they consistently have a flat spot on the bottom caused by the weight of the car acting on the air pressure held in the tyres. Even at 100mph the centrifugal force isn't sufficent to get rid of the flat spot.
This is designed into cars from the start - some manufacturers do it better than others (Audi are very good).
As the tyre wears, there is barely a variance in speedo reading (from brand new to worn out, the effect on the speedo would be less than 1%)


Quote:
Originally Posted by dicktahoe View Post
I think you may be reversing Speed reading with Odometer reading. Odometers are not permitted to read high. That is--they cannot indicate you have traveled 105miles when you only went 100 (that would reduce your warrantee for one thing). But the Speedometer reads a few mph higher than you are actually going. When I read 75mph, my GPS says I'm only doing 72. That keeps you from unintentionally speeding.
Thanks, you made me realise my error - I was correct in my assertions about design rules for speedos, but had my over's and unders mixed up - meant over when I said under and vice-versa! I've corrected my original post now (corrections in bold text)
...also included as excerpt from the Australian Design Rules (which are based on UN recommended standards, which most manufacturers now adhere to internationally)
__________________
Cheers,

Marty



Current:
2001 Audi S8
- Solar Sunroof, heated front and rear seats (just what you need in Australia!) Tinted side and rear glass, RNS-D, XCarLink, Bose, clunky old phone in arm rest!

Sold:
1997 Audi A4 Quattro - 5spd man "Hamilton's Club Sport" - will miss the old girl!
twentysevenlitres is offline   Reply With Quote
Old 05-27-2014, 03:30 PM
AudiWorld
Audi R8




Paid Advertisement
 
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 05:23 PM.


Copyright 2014 AudiWorld.com Audi Enthusiast Community