Are BMW speedo's accurate?

[chippy69]

I know that many speedo's are purposely calibrated to show a slightly higher speed but I was under the imopression that people like BMW and Porsche make their speedo's more accurate than others, is this true.
I am only asking as I hit (naughty) a fairly high speed over the weekend in my E30 M3 with quite a few revs left on the counter and am just wondering if it was accurate!

[Zod]

My E46 M3 speedo is about 5mph out at speeds in three figures according to my Road Angel.

[xxplod]

BMW are no more accurate than anyone else. My force has 330 diesel estates for area cars. They have the standard equipment speedo, and they are equipped with a digital cailibrated one on the dash, for doing "speeders." The standard speedo over-reads by approx 5 - 8%.

[chippy69]

I knew the minute I posted this a policeman would reply! I promise it was for a very short time officer and late at night and in Europe
I'll deny everthing!!

>> Edited by chippy69 on Tuesday 16th March 14:10

[li'l pugs]

Can only tell you what my mates 2003 M3 is like. 160 on the speedo, 152 on the GPS gadget thingy. 180 on the speedo and 167 on the GPS gadget. Both on private roads etc etc etc

[iguana]

Pre 996 Porsche speedos are in my experience can be just as inaccurate as every other car when the speeds are very high, like 190mph on speedo= only 170mph or so on GPS, although some older porkers can read suprisingly near to the mark even at 160+

My old Corrado is 10mph optimistic when speedo at 125 & my bike speedo read a whisker off 150 when at at 130.

Only way to know for sure is to take a portable GPS with you & find a nice empty bit of road, *ahem* I of course mean private test facility

Ted, Bluesatin & a few others can tell you how accurate their E46 speedos are after Sunday

[pvapour]

178mph gps = 182mph speedo - M5, Autobahn I might add on the way back from Geneva which I thought was pretty accurate?

Nik

edited to addd this, not mine, someones in the states, god knows if it's acurate there's no numbers round there



>> Edited by pvapour on Tuesday 16th March 20:14

[DustyC]

I read some where on here once that depending on satelite positons (the distance between them and the angle of signal) the GPS signal can actually be quite in acurrate.
Then again, there isnt really much else to measure buy, unless you can time yourself over a known distance.

[dcb]

chippy69 said:

I know that many speedo's are purposely calibrated to show a slightly higher speed but I was under the imopression that people like BMW and Porsche make their speedo's more accurate than others, is this true.

It's true under UK law that speedos have to overread by a little bit from 0-70mph.

Faster than that, no UK requirement.

However, for German manufacturers, they will have to stick to the DIN standard, which I've forgotten. Google maybe ?

chippy69 said:

I am only asking as I hit (naughty) a fairly high speed over the weekend in my E30 M3 with quite a few revs left on the counter and am just wondering if it was accurate!

M3 governed down to 155 mph, I believe - i.e. swift but not fast.

You have to go to non-BMW kit for faster.

[The Wiz]

Didn't think the E30 M3 had a limiter.

[chippy69]

The Wiz said:

Didn't think the E30 M3 had a limiter.

I don't think it has either but it has got a rev limiter (I know as I have hit it a few times)

[chippy69]

Thanks everyone for the info

[fergus]

The E30 M3 only has a rev limiter. I have seen an indicated 250kph on the speedo. (downhill from germany into Belgium on the E40!).

[chippy69]

fergus said:

The E30 M3 only has a rev limiter. I have seen an indicated 250kph on the speedo. (downhill from germany into Belgium on the E40!).

that is quick Fergus, btw how is your insurance nightmare coming along?

[AC79xxx]

fergus said:

The E30 M3 only has a rev limiter. I have seen an indicated 250kph on the speedo. (downhill from germany into Belgium on the E40!).

Saw mine go off the clock in Geneva although it's only geared to do 154mph which is what I expect I was doing when I hit the limiter in 5th

[Zod]

I've had both of my M3s indicate 170 on the speedo in Germany. Road Angel said 162/3. First time, I was playing with an M5 on a deserted stretch of Autobahn (these do exist in Germany)on a Sunday afternoon in summer.

[xxplod]

Incidently, I don't believe speedos have to overread. I believe (DVD - advice??) that speedos can be 10% inaccurate either way.

[granville]

pvapour said:

178mph gps = 182mph speedo - M5, Autobahn I might add on the way back from Geneva which I thought was pretty accurate? Nik

The nectar of life.

Hail to thee.

[m-five]

xxplod said:

Incidently, I don't believe speedos have to overread. I believe (DVD - advice??) that speedos can be 10% inaccurate either way.

They are not allowed to under-read at all!

[The Admiral]

'98 M Roadster on standard wheels/tyres over reads by 2-3mph all the way from 30-159mp/h (GPS) - then hits the soft rev limiter