E39 - 530 or 540?

"maxima1" > wrote in message
om...
> Just passed a roadside radar display this morning. Speedo read 53,
> while the radar says 49 mph. Must be designed to reduce tickets?!?

Few weeks ago while driving towards the track I tested speedo on my E36.
While driving 110 km/h (according to speedo) GPS says 106 - 107 km/h. On the
way back I put it on 70km/h and GPS showed 66 - 67km/h. Right at that time
policeman was checking my speed with a laser (it happened within city
limits, 50km/h allowed) and laser has shown I was going 68 km/h :-)
As well my top speed according to speedo is 220 km/h (rev limiter prevents
the car to run faster :-) ), which would be around 216 as its mentioned by
the book.

--
Regards;
t.

"Dave Plowman (News)" > wrote in message
...
> In article >,
> maxima1 > wrote:
>> > > Roadspeed seems to be spot on, though.
>> >
>> > That's a first for BMW, then. ;-)
>
>> Just passed a roadside radar display this morning. Speedo read 53,
>> while the radar says 49 mph. Must be designed to reduce tickets?!?
>
> I dunno. Since I know my speedo over-reads, I just make allowances when
> passing a speed camera.
>

Of course, I was referring to the OBC speed reading, not the speedometer.
My speedos read pretty consistently about 3-4% high but you can easily check
them with the OBC, so I can live with that. The worst one I ever had was a
'76 R750/6 which read 125 mph at a true top speed of 104!

Tom

"Dave Plowman (News)" > wrote in message
...
> In article >,
> John Carrier > wrote:
>> Two E39's that both had an optimistic speedometer (by BMW design as it
>> turns out, to comply with German law)
>
> Don't know German law, but I doubt it. In the UK a speedo may be either
> accurate or over-read by up to 10% at 30 mph. It must not read low.

Same basic thing. In Germany, your speedo may not read low. To insure
against that possibility, its designed to read high.

> This reg dates back to the days of mechanical devices where such a
> tolerance may have been necessary. Not so today.
>
> Of course many makers made use of this loophole - it makes the car appear
> faster to the gullible. But several had speedos which were as near as
> dammit accurate - even in the days of eddy current types. Jaguar, Rover
> and Rolls Royce are but a few.
>
> --
> *How much deeper would the oceans be without sponges? *
>
> Dave Plowman London SW
> To e-mail, change noise into sound.

In article >,
John Carrier > wrote:
> > Don't know German law, but I doubt it. In the UK a speedo may be either
> > accurate or over-read by up to 10% at 30 mph. It must not read low.

> Same basic thing. In Germany, your speedo may not read low. To insure
> against that possibility, its designed to read high.

This is a nonsense, given the consistency of them reading high. If it were
just for production tolerances, there'd be more of a spread.

And in this day and age, do you really believe it's difficult to make a
device like this that betters 10% accuracy?

It's a deliberate act by BMW. Why, I can only speculate.

--
*If you think nobody cares about you, try missing a couple of payments *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" > haute in die Tasten:

> This is a nonsense, given the consistency of them reading high. If it
> were just for production tolerances, there'd be more of a spread.
>

First I can confirm: In Germany it is the law that a speedo must not read low. It may
read high, as far as I know the limit is 10%, but I am not sure about this. The reasons
for misreading speedos are not necessarily production tolerances. One has to keep in
mind that many cars can be equipped with different tire sizes, which often differ in
their diameter. And a new tire has up to 10 millimeters more diameter than one which is
worn out. In addition to that older BMWs in general seem to have quite optimistic
speedos. The one in my E30 reads about 10% high at any speed, while the speedo of my
Citroen is very accurate indeed. Given the fact that my Citroen sedan has a softer
suspension and a lower inside noise level, this has lead to the side effect, that I
unconsciously drive my Citroen a little bit faster in any situation, compared to my BMW
(okay, got only one speeding ticket in one year).

Frank

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Citroen - Made in Trance

In article >,
Frank Kemper > wrote:
> > This is a nonsense, given the consistency of them reading high. If it
> > were just for production tolerances, there'd be more of a spread.
> >

> First I can confirm: In Germany it is the law that a speedo must not
> read low. It may read high, as far as I know the limit is 10%, but I am
> not sure about this. The reasons for misreading speedos are not
> necessarily production tolerances. One has to keep in mind that many
> cars can be equipped with different tire sizes, which often differ in
> their diameter.

Then you'd expect it to be accurate under the 'worst' condition - but it's
not. And in these days of electronics it would be child's play to have the
speedo programmable for different wheel/tyre combinations - after all
there are already many options which can be set by the dealer on things
far less important than this.

> And a new tire has up to 10 millimeters more diameter
> than one which is worn out.

If the speedo started out accurate with fresh tyres, it would read
sightly fast as they wore, thus complying with the legal requirements.

> In addition to that older BMWs in general
> seem to have quite optimistic speedos. The one in my E30 reads about
> 10% high at any speed, while the speedo of my Citroen is very accurate
> indeed. Given the fact that my Citroen sedan has a softer suspension
> and a lower inside noise level, this has lead to the side effect, that I
> unconsciously drive my Citroen a little bit faster in any situation,
> compared to my BMW (okay, got only one speeding ticket in one year).

I've also got a non BMW with an accurate speedo. And this model had a
variety of sensors fitted to the 'box for the various final drive ratios
and wheel sizes.

--
*If all is not lost, where the hell is it?

Dave Plowman London SW
To e-mail, change noise into sound.