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      08-25-2008, 01:51 PM   #62
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Originally Posted by Wads View Post
Has anyone tried to compare and contrast the actual acceleration curves between the different modes yet (I'm sure somebody will have done this?!?!)..... I pick up my M3 next Monday and plan to time it in the various modes (once run in) using a Racelogic PerformanceBox (used by many of the top car magazines)...... if anything interesting shows up i'll post up the results.
You could try this. These preliminary results are not at all controlled enough to compare them directly (not even identical throttle used in all cases). Better yet you should compare velocity vs. time curves. You need to numerically integrate the acceleration signal to get velocity vs. time. This would be basically just like using a Vtech or similar acclerometer based device. As you can see these signals are pretty noisy and that is going to be a problem. It would probably be much better to test for this in a more direct fashion with an arm/wheel tester more commonly used for vehicle performance testing. The effects are fairly small so you probably would have to make a lot of runs and then average the results to see the difference (no matter which method was used). Also, if you had two cars that could otherwise be seen as nearly identical you could just do an direct head to head test only changing the Drivelogic mode.

You should be fairly convinced of this effect just looking at the data I already posted. You can clearly see a longer duration and increased acceleration profile which is consistent with what you feel. You can easily calculate the extra velocity just as I did in my OP and despite the simplicity of that calculation it should be quite accurate (I basically just smoothed and averaged the curve and then numerically integrated it "by eye"). Once in gear everything will be identical. You only get the changes right during the actual shift events. You will get these tiny bursts of extra velocity comparing modes with surge vs. those without (just like it feels!).

We'll certainly be interested in your Racelogic results.