I got my new '04 S4 last March. I noticed that at speeds that I was
normally keeping up with traffic or going slightly faster in my old car, I
was now being passed quite regularly in my S4. So, I do the natural
response and speed up. I figured the speedo was reading about 5% high, so I
asked the service guy at the dealership. He said it's a new federal mandate
that speedos on cars 2004 and new must read 5-10% high. He didn't really
have an explanation and was not happy about it either because he has to tell
people that there's nothing he can do to fix it. The only thing he said was
that it was so that people will think they're going faster than they really
are so that if the speedo's reading 70, they'll really be going closer to
65. What a load of crap! Do the stupid politicians actually think people
won't figure it out? If not just by driving, but if they do get a ticket or
go by one of those speed readout boards, people will figure it out. Has
anybody heard about this?
Nothing has changed, nor is it unusual. Maybe the US has just caught up.
AIUI, legislation in the UK has required (for years now - maybe came
from a European regulation) that speedometers read between +1% and +11%
at 70mph. In other words, by law speedometers must never under-read.
It's an obvious safety provision, as well as protecting manufacturers
from frivolous claims by motorists who are being prosecuted for speeding
and want to blame somebody else.
It happens that my old A3 over-read by about 5mph at 70mph, but my new
A3 over-reads by about 1-2mph at 70mph. When I first got the car, I
double-checked the speedometer against the speed reading from a GPS. I
want to be confident about my actual speeds.
The reason that I'm anal about speedometers is because I bought a new VW
Golf in 1998 which did have an under-reading speedometer. Needless to
say, the dealer refused to believe me and tried hard to patronise me as
someone suffering from delusions. When I became insistent enough for
them to check, they were forced to replace it PDQ especially after I had
pointed out to them that they had sold me a car which was illegal to use
on a road. It was under-reading by about 10%, and it was obvious when
driving in traffic on a motorway.
If you carry out the same calibration yourself, you might also find it
very educational to watch how much other cars slow down for speed
cameras or around traffic cars, when you know they're already doing less
than the speed limit. A reduction of 11% at 70mph means they are
actually doing less than 63mph. It seems that many cars' speedometers
over-read by near to the maximum, if only the owners realised it.
Yes, I have had a traffic car tuck in behind me after I had sailed past
them and everyone else doing 65mph, only for them to leave me alone
after following me for a couple of miles. I like to think that it would
have been plain to them that I did know what speed I was doing, unlike
most others on the road it seems, but who knows?
N.B. Email sent to "nospam" will be rejected. Please use Reply-To address.
The Road Vehicles (Construction and Use) Regulations 1986, as amended,
allows the use of speedometers that meet the requirements of EC Community
Directive 75/443(97/39) or ECE Regulation 39. Both the EC Directive and
the ECE Regulation lay down accuracy requirements to be applied at the
time of vehicle approval for speedometers. These requirements are that the
error in the indicated speed must not be more than 10 per cent of the true
speed plus 4 km/h. The requirements are also that the indicated speed
must never be less than the true speed.
Hi Peter, yes I am an owner of both an allroad and a Sony RDR-HX710.
Speaking of which, does anyone know whether the DVD drive in the Audi Nav+
RNS-E is intended to be able to play DVD movies, or is it only a DVD ROM
drive for navigation map files and MP3s?
I just tried putting a film DVD into mine and the disk was not recognised.
There is no such thing as an "accurate" speedometer that used engine speed
and gear ratios to calculate speed. Your indicated speed varies according to
amount of tyre wear and whether the tyre is over or under inflated.
You the driver would certainly sue the manufacturer if booked for speeding
when your speedometer indicated you were travelling within the speed limit.
For that reason all car makers have sold cars with over-reading
speedometers, long before any law made them do such a thing.
A GPS system is certainly much more accurate as it is not affected by things
like tyre condition. Obviously such a system cannot replace the cars
speedometer as it cannot work anywhere the satellites cannot be seen.
It would also help if some smart-alecs would shut-up instead of writing
bullshit on things they obviously know nothing about.
I wondered that too. My 2002 A4 also reads exactly the same as those speed
boards at all kinds of different speeds. I tested the speedo by driving at
exactly 60mph between two mile markers and timing the run using a
stop-watch; time was within a tenth of 60 seconds. I repeated the test at
70mph and 80 mph. That also gave an accurate result. So, as long as the
mile markers are accurate, the speed boards and my speedo are within 1% of
the true speed. My '95 Passat was within 2%. Then again, I once used a
radar gun to clock an airplane hanger at Sebring at 57 mph :-)
OK, you've had your fun, now can any of you find me a maker who guarantees
their cars speedometers are 100% accurate all of the time?
Maybe it would be wise to search Google before trying to redicule someones
statement first. Or as they say "engage brain before pressing keys".
Have a nice day.
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