it could be that your transmission shift mode is set to be aggressive. The transmission adapts to your driving style as you drive and it might be that it thinks you are a lead footed driver. Check with your dealer so he or she can reset the software to re-calibrate the transmission shift mode.

I have a 4.8i as well and I got the software reset. its smoother now but just be easy on the car after you get it done so that the transmission software can adapt to your style correctly

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2007 4.8i Space Grey, 20", black nevada interior
All options with no 3rd row, rear entertainment,
handling pkg.