I have calculated the optimum shift points for the BMW 328i with a stock M52 engine.  The hp/torque data was taken from BMW Technical Bulletin 11 75 96 and 205/60R15 tires were assumed.  The green lines are the rear-wheel power curves (in kWatts/10) for each forward gear, assuming 15% drivetrain losses.  The cyan lines correspond to rear-wheel tractive force (in Newtons, again assuming 15% drivetrain losses) for each gear, while the yellow lines correspond to engine RPM.  As can be seen on the graph, the points where the power curves cross each other (equal power before and after the shift) also correspond to where the rear-wheel force curves cross each other (equal rear-wheel torque before and after the shift) and result in the best acceleration.  Please keep in mind that a different final drive ratio or tire size will shift the curves in the horizontal axis (shift point speed will be different), but the optimum shift point RPM will remain the same.

BMW did a good job of choosing the gears for driving in the track or autobahn from 70mph up to 140mph and above.  The engine is turning just past peak hp RPM in top gear during actual top speed and 3rd - 5th gears keep the engine on the power band.  However, it's worth noting that this great high-speed ratios come at the expense of 1st and 2nd gears, which are spaced a little far apart.  At least BMW did the right thing and didn't sacrifice high-speed performance to get better 0-60mph and 1/4 mi. times.  After all, BMW's natural environment is at the track or Autobahn, not the drag strip.