What we need here (or in any case, gas/diesel alike) to determine optimized acceleration is to plot rear wheel torque against road speed for all gears then assess the intersection of each gear plotted to the next to see at what point a shift will result in maximized area under the curve. With the narrower ratios of the 8HP70, I too would think that going right to the red-line may actually cause more of a drop in rear wheel torque available than dropping down solidly into that much stronger, flat-rated mountain top of torque in a numerically taller gear.
Anyone have a torque plot of the 50d N57?
2009 335d Sport - Space Grey
, Gloss Black
on Black Leather