Please don't chastise me. But in the name of science I took my A4 out
on an empty highway near me yesterday. After some test runs up and
down this road to nowhere, looking for speed traps. I tested to see
if it was indeed programmed not to exceed 130MPH. At 135MPH I felt my
question had been answered. At that point I asked myself, "What are Y
rated tires good till?" At that point I let of the gas and two mile
later I was back down to 75MPH, it felt like it could have gone faser,
and the car felt great.
On Mon, 11 Apr 2005 17:52:39 GMT, email@example.com wrote:
At an indicated 135mph, I'd expect you to be doing less than 130mph.
Does that climate control hack that shows you the speed in KM work on
a 2003 A4? It might be worth seeing what that says. Of course, looking
down at the climate control screen whilst doing 130mph might not be
the smartest course of action!
There's error in the speedo so what you observed is not entirely out
of place. I'm sure the ECU is using an electronic measurement of speed
from some sensor that's no doubt more accurate than the speedometer.
Well, I'm not doubting that it makes sense to have a speedo which is
showing a little more than the actual speed. It's the law here as
But I'm wondering where the ECU/Air Conditioning display should get
different info from.
IMO it's just the same information shown on another display.
The speedo shows a little less than the actual speed.
Both the speedo and the Air Con display get the speed from the same place
(usually the ABS Sensor) but the speedo is calibrated to show a little less.
I actually like this 'feature', as I tend to drive around about 10 mph
higher than the posted speed limits, which generally the police will
let you have - so in the case of the Audi, an indicated 10 mph over is
really more like 7 mph over, which is better for the driver's
Central NJ USA
Audis and VWs are designed to show a higher than actual speed on the
speedo. The ECU knows the real speed (to within the accuracy permitted
by variations in tire size due to wear, etc.) and there's a trick you
can do with the Climatronic to get it to show the true speed. (On the
Passat, it's fan-down, temp-down, and Econ all at the same time, then
use temp-up to reach option 16 - don't know if it's the same on an A4.)
I recently did this on my Passat and found that the difference was
about 3-4 MPH at 50.
I have checked the speedo in both my A4 (2002) and Passat (1995) by timing
the interval between mile markers on the highway at a constant speed
(65mph). Both were within 1mph of the calculated result.
Indeed, prob. < 120mph. If you can, borrow a GPS unit which will give
you a more accurate "actual" speed. My GPS unit tells me that when I'm
doing 70mph, it's actually 65. The differential gets greater the faster
you go (compared to say 30 mph).
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