[sdorn]

Kill this thread.

[ben1364]

Have you ever owned a motor vehicle that was equipped by the factory without an optimistic speedometer? This is not a BMW thing.

[ward]

also the fuel gauge is pessimistic

[sdorn]

Originally Posted by ben1364

Have you ever owned a motor vehicle that was equipped by the factory without an optimistic speedometer? This is not a BMW thing.

I currently have a Ford F-150, Mustang, and I just got rid of a Saturn SC2. All three of them had accurate speedometers that matched the GPS readings exactly. In fact I have owned more than a dozen cars, both foreign and domestic, and this is the first one with an inaccurate speedometer.

[Geneb2450]

If the odometer was off (recording more mileage than what you really traveled) then I'd certainly be concerned as the warranty would expire prematurely. I'm curious what tires you run. Tire circumferance may have an effect on displayed MPH. Not sure where BMW speedometer gets it raw data from though, but changing tires to a lower aspect ratio on my Prelude had the effect you described.

[obLu]

Meh, seems like a non-issue to me. Can't imagine getting so worked up about it that I wouldn't buy another BMW. Where's the safety issue at?

As long as I'm moving faster than the traffic around me, what do I care what my exact speed is .... until I see the trooper on the side of the road I'm rarely looking at the speedo. I'm looking at the cars around me.

[E90Fleet]

Most european cars are like that

They have to make shure that even when the approved tire with the most tread is on the car that the spedo will not read over the actual speed ( you will find there are diameter differences between makes of tires, eventhough they are the same spec ).

If your actual speed was 61MPH and your guage read 60MPH you could take the manufacturer to court if you recieved a speeding fine.



Also remember if testing by GPS to do it on a level road. If you are going slightly downill or uphill the unit would show your speed differently than your speedo would. ( if you fall straight downward at 100MPH [ or any speed ] your GPS would show your speed as 0 )

[obLu]

PS. usually the odo and speedo pick up is in the transmission ... but yeah, running smaller circumfrence tires than it was designed for (+/- a certain %) will impact both speedo and odo readings. Because you're effectively changing the final drive ratio.

I'm pretty sure that as long as you're +/- 10% the automaker isn't going to take notice.

[E90Fleet]

Originally Posted by Geneb2450

If the odometer was off (recording more mileage than what you really traveled) then I'd certainly be concerned as the warranty would expire prematurely. I'm curious what tires you run. Tire circumferance may have an effect on displayed MPH. Not sure where BMW speedometer gets it raw data from though, but changing tires to a lower aspect ratio on my Prelude had the effect you described.

If you change your tire profile to a non-oem size your speedo and milage would be wrong in any make of car

[sdorn]

I have the stock wheels and tires. The car is only two weeks old. I tested using the GPS multiple times over long stretches of interstate with the cruise control set at different speeds, and the difference was constant between the speedometer and the GPS.

Driving around Atlanta I don't have to worry about the speedometer that much because there is a lot of traffic around, and like was mentioned above you just stay with the flow. However, I often drive on interstates in rural areas where there may not be any other traffic. I need to be able to set my cruise control at a precise speed (within 1 mph) in order to make the best time while at the same time not have to worry about getting a ticket. This has never been a problem with any other car.

Plus, it is just one of those things with me. I need my clocks to be set within seconds of the atomic time. I need my speedometer to be accurate. I need my thermostat to maintain accurate temperatures. I expect instruments that measure something to be accurate, regardless of whether it is in my car or anywhere else.

Whats worse is that the car knows the correct speed. If you get into the unlock menu and display Menu 8 that shows the actual speed, it is correct within 1-2 km/h which would be great. Why would a car have the accurate information available, and then display inaccurate information? It makes no sense.

[dtelle]

it is not exact your remark about a delta between GPS speed and speedo.
all GPS chips are able to calculate the "3D" velocity if the GPS is able to track more than 4 satellites (better 5).

I am speaking from the signal send by the GPS to the computer. then the computer can of course project this velocity vector on the ground, loosing the vertical velocity. But with the rigth software on my pocket PC, i am able to read the 3D velocity (taking the GPS in my Hand and moving the GPS from my head to the ground, it is able to measure the vertical velocity (with enough satellite signal of course).

On the other Hand no idee how is managing the i-Drive in a BMW.
At least my pocket PC with his bluetooth GPS is giving me my "absolute" velocity

[YV1]

Even your GPS is not 100 % accurate. Read the GPS manual, it is on it. Your BMW speedometer has a 5% error. There is like 1-2 % diference on your speedometer betwen brand new tires and worn out tires. It is impossible to do it better than this. Why would any cop give you a ticket for less than 9 miles?

[obLu]

I need my clocks to be set within seconds of the atomic time. I need my speedometer to be accurate. I need my thermostat to maintain accurate temperatures. I expect instruments that measure something to be accurate, regardless of whether it is in my car or anywhere else.

Hahaha, that's the real crux of it; my wife's the same way ... if she knew the speedo on my car was that off she'd freak too. I probably shouldn't tell you how much time the car's clock looses per month should I?

[shragon]

i agree it's off too. around my work, we have a couple the electronic speed limit signs which tells you how fast you're going and to slow down if you're going to fast. i was going 30 mph in the 325i, and the speed on the sign said something like 27 or 28 mph.

[SteveMD]

Next on E90Post.com: The orange dashboard lights are too orange.

Seriously, the speedo can be upto 10% in error and still be legal.

I don't know about our E90s but when I put a bigger wheel tire combo on my Suburban, I had the ECM reprogrammed to reflect the new size. Speedometer is accurate (compared to my Garmin 330 GPS).

[sdorn]

Originally Posted by esteller

Why would any cop give you a ticket for less than 9 miles?

In Georgia, cops won't bother pulling you over for 9mph over the limit. Most won't give out tickets for less than 14mph over the limit, as they don't go on your license anyway. When I travel on rural interstates, I set my cruise control at exactly 82mph (70mph limit). With the speedometer in the BMW, I can't do that. I have to guess at what speed is really 82mph. It is somewhere around 86 or 87mph, but I am just guessing. Then when the limit drops to 65 or 60, I have to guess at what is 12mph over that. I shouldn't have to do that. If they can put an accurate speedometer in a used $6k Saturn, they can put one in a $40k BMW.

[shragon]

actually, i have no problem with the speedo being off. i tend to have a lead foot, so it may actually save me.

[sdorn]

Originally Posted by SteveMD

Seriously, the speedo can be upto 10% in error and still be legal.

That is a ridiculous excuse. Who cares what is legal. They are intentionally giving us inaccurate instruments in what is supposed to be the "Ultimate Driving Machine". That is just ridiculous.

[akhbhaat]

Originally Posted by sdorn

We need to start a campaign to get BMW to address this issue. If all the members of this board and any other boards we can get to participate suddenly started taking their cars into their dealers to complain about the speedometers, that would cause a huge backlash at BMW. It might be enough to get them to fix the problem. Sending letters to BMW would also be a great idea, like one every week.

Yeah, you're definitely a first-time BMW owner.

[obLu]

Me thinks your SA is the normal barely knowledgeable ticket taker and just made up some crap to keep the shop guys from laughing at him for creating a worthless work order. I highly doubt it's "intentional". I think it's more that they just don't care.

[JackMac]

BMW has done this (optomistic speedo readout) across the product range for many years. One more thing to make your car unique from the crowd.

[E90Fleet]

Our local car magazine uses a calibrated wheel that is attached to the car to detemine speedo accuracy, and I can tell you there isnt 1 car that is 100% accurate, no matter what the make

1 or 2 cheap makes overread soometimes, but the rest always underread.


Also you can have a 100% accurate spedo on 1 set of tires,but wear those tires down a bit or change to a different make of tires and the reading will be different