[swagon]

Originally Posted by champignon

This is not news. As I posted, my 135is, with the 17" rims and square winter tire setup reads slightly (1mph) slower on digital, uncorrected readout compared to what I got yesterday comparing to a smartphone GPS program. I ran the comparison at multiple speeds, from 35 to 65 mph (I was not driving on roads with a higher speed limit than 55 in my brief testing yesterday; the closest 65mph road to me is about 12 miles away). I consider that acceptable, nothing is perfect.

When that same speed input is "uncorrected," as with the analog dial speedometer, (or with the digital readout if I don't have Carly "uncorrect" what BMW would like to "correct,") then the readout is 4mph faster than actual.

I am not expecting perfection, and if the system is going to make an error, it should be small and should be biased to showing a slightly slower speed than actual speed.

What I have a problem with is the INTENTIONAL doctoring of the speed shown to mislead the driver into thinking he is going faster than he is actually going. I was told by my service advisor on my last visit to the dealer (with my newly purchased used 135is convertible) that they could not correct the under reported speed because this was an INTENTIONAL SAFETY FEATURE put in there by BMW in their vehicles. She initially told me that this was her impression but that she would check with the tech and with BMW NA itself, which she did.

The fact that the Carly program gives you the option to report in the digital speed, the actual measured speed or the "corrected" speed gives independent verification to this quite obvious fact.

TL;DR