[james4321]

Guys,
I checked acceleration of my stock 335i F30 today. Just recorded a video and frame after frame checked 100-200kmph pull on the gauge. Result is 13.5 sec (2 persons + luggage and some beers &#128512 . Then I realized that speedometer is not accurate compare to real speed. I know those measurements are not as good as apps/RaceLogic is. But, does anyone know what is the speed on speedometer if I want to check real 100-200kmph?
Maybe someone has some app to check it for me?

[Billfitz]

The speedometer typically reads 3% low, although that's affected by the tire size. 100 to 200 kph actual will be in the vicinity of 103 to 206 kph on the speedometer.

[james4321]

Originally Posted by Billfitz

The speedometer typically reads 3% low, although that's affected by the tire size. 100 to 200 kph actual will be in the vicinity of 103 to 206 kph on the speedometer.

Thanks. So now (103-206) it shows 14.5sec. With extra 100kg. I’ll check without it. :-D

[Billfitz]

You can lower it by taking your tires up to maximum pressure, but you wouldn't want them that high for daily driving. Gas mileage will be better, but they'll ride harder, won't hold as well when cornering and won't wear evenly across the tread.

[james4321]

Originally Posted by Billfitz

You can lower it by taking your tires up to maximum pressure, but you wouldn't want them that high for daily driving. Gas mileage will be better, but they'll ride harder, won't hold as well when cornering and won't wear evenly across the tread.

This car is my daily. I don’t want to be the fastest in the city. Just curious if my 335 is stock, like it should be. It’s enough for me.
But, do you think this additional 100kg makes a difference when it comes to a 100-200kmph times?

[Billfitz]

It will make some difference, but not enough to matter. Above 100 kph the main limiting factor to acceleration is wind resistance.

[Skyhigh]

The measurement you have performed with a video and the speedometer is HIGHLY inaccurate. It is only usable as a reference for yourself, if you are to introduce changes and would like to compare "before" - "after" for a binary "yes, there is an improvement" or "no improvement".

I was shocked that even a measurement with BMW's "Laptimer" connected to the car is appreciably inaccurate! (nearly half a second for 0-100).

So don't take the numbers as actual value...

And yes - weight matters. Maybe less for 100-200, as it does for 0-100, but it still does. 100kg is ~6% increase...