calpalmer

If the Magellan confirms that your BMW speedometer is ~ accurate, you may be able to have it replaced by a Dealer for one that is 3-4mph higher. The Ultimate Driving Machine, don't forget!

Let us know what it says,

Cal

bimmer530iguy

My speedometer meter is always sitting at 2-3 mph when the car is not moving, and even when the car is off. Also, when I decellerate the speedometer doesn't drop with the speed when I am coming to a stop. Also, my car gives inaccurate speeds of +5-7 mph above the speed my GPS and speed radar readings. It was never this bad but it is getting worse, is it because I of the 20" wheels, which is throwing the speedometer off consistently?

juris335

It is uncomfortable for me to think BMW would be so paternalistic as to set my speedometer to read fast. Every BMW I have owned (3s, 5s and 7s) has had the speedometer read fast - and progressivley faster. Same with Volvos. Thus, when it reads 50 I am going 47. When it reads 80 I am going 76. I have not checked my 2008 535 yet.

calpalmer

See above. I am fairly certain there is a regulatory reason for this, at least in Germany and perhaps elsewhere in the EU... Maybe some of our German members can confirm??
Cal

SergeyM

My 2002 540 (E39) was progressively fast. Showed 50mph when the real speed was 47mph, 105mph for the real 100mph and 150mph for 140.
Boths E60s are much better in this respect with +2mph at any speed.

khangnguyen

i go by the multiple speed radars multiple times a day and it always reads 3mph lower than my bmw speedometer...i was always wondering if that would effect my odometer but i guess not what from you guys were saying...i will ask my dealership!

Phantom Mark

I saw a scale either on these forums or the E46 forums showing how the speedos are scaled vs real speed, its a deliberate thing as you know already, Aparantly it could be corrected via some adjustment in the electronics or something, not sure, not my field to be honest, mine is also the typical 3mph wrong at most speeds

DD_545i

I can't believe there were so many posts in this thread without one person yet stating why the speedometers are **ALL** inaccurate.

ALL speedometers are inherently inaccurate. It's a very difficult task to display the correct speed at all speeds. You're either 100% accurate around low speeds like 30mph, or you get mid-range speeds like 90mph right, or you get the upper speeds like 150mph right. No speedometer has ever been fully accurate at all of them.

So, with speedometers being basically inaccurate to some extent, what's a manufacturer to do? They only have one option and that's to tune the speedometer so that it under-reads by a couple or three mph. The result of doing that is that you'll get a range of inaccuracy of between 0mph and perhaps as much as 5mph, but it will ALWAYS be under reading.

Imagine the situation where they weren't under-reading. You look at your speedometer and it's showing 55mph and you're in a 55mph zone, and you get a speeding ticket for doing 57mph. How quickly will the American lawyers be all over that and suing the car manufacturers? Oh you bet there'll be a lot of class action law suits, especially in America where two thirds of all the lawyers in the world live (to service 5% of the world's population).

Simple fact about it is, speedometers are inaccurate generally, and car manufacturers adjust them to under-read because nobody can sue them for displaying 55mph when you're actually driving only 52mph.

The person who said their speedometer was spot on accurate, try it at lower and higher speeds and you'll find it under reading. You must have found a lucky sweet spot where it matched the GPS speed. If BMW were to notice it, they'd adjust it to under read a bit more for you

Whenever I'm setting my cruise control on a stretch of road with a high risk of mobile police radar guns appearing, I always add an extra few km/h for speedometer inaccuracy.

suthurnbimmur

This is funny I ran into this thread cuz I have been wondering the same thing. I have that speed enforcement trap in my area and my speed is always showing less than whats on my speedo, about 5kmh less. But when I drive my Escalade, its pretty much right on. Well, Im glad to know atleast I was not the only having this issue or atleast it is an issue with BMW cars..............

calpalmer

I don't really disagree with what you're saying.... but I think it's more than this (i.e., the American litigiousness...). If that's all it was, you'd see ALL manufacturers doing the same things with their speedo's, but most do not opt for the 2-3mph at 60. But several German and Scandanavian manufacturers do, and as I said earlier I have read somewhere that there is a regulatory reason for this.... Can't verify it, and can't really remember where I read this, but maybe someone from the continent will embellish.

Cal