Quote:
Originally Posted by x5mad
The 128 has an inferior automatic gearbox compared to the 135 and also the gearing might be diffrent which will also play a role.
So for 135 manual ratio = 3.06, auto = 3.46, this shorter gearing combined with good gearbox acts to close the gap between the manual and auto.
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I noticed that, but in your conclusions you might be wrong.
I compared several E87 123d and 130i (Euro cars) and look at figures, too.
MT AT
130i 0-100 km/h 6.0s 6.2s
123d 0-100 km/h 6.9s 7.0s
The point is how harmonically develop engine's power with shifting algorithm.
When I changed ECU software and brought 125i power to stock 330i level (272 HP) I carefully compared car real world performance with both 130i MT and AT.
Due to fact that 125i has even shorter final drive ratio than 130i, it was not surprise that 125i with AT was slightly quicker than both stock 130i both with AT and MT (7 HP more are compensated with some 40 kg more weight of tested 125i).
Both stock 125i and US 128i show very big difference in result between MT and AT, although on 125i is exactly same gearbox as on 130i (and I believe 128i, but didn't check this). With power elevated to around 130i stock values the difference evaporated.
So, the difference (0,7 s in Euro spec) was melted down when engine characteristic became better optimized to initial characteristics of the gearbox.
Practical conclusion is that acceleration difference here depends on engine and ECU algorithm much more than gearbox itself.
After further power enhancing (to around 300 HP) power gains were clearly reflected in car acceleration and feel (further around 0,6 s improvement 0-100), so car, although not exectly same, can hold its own very, very close to 135i (both AT and MT).
I believe that 135i has heavier duty gearbox (not better in terms of acceleration) due to its huge torque in lower revs (here is the biggest difference to N52 engine).