I have a 2011 128i with sports package and manual trans - the most recent of several BMW's I have owned over the last 20 years, including some "M" models. My 128 now has 13K miles on it. I've found the 128 has plenty of power for typical passing of slower traffic, without downshifting or by downshifting just one gear. If I really want to pass very quickly, I might downshift two gears. I have found that the 128 has plenty of power for any sane real-world driving.
My wife and I have just returned from a 7,000+ mile driving vacation in my 128i; and I am still very happy with this car. About mid-way through my trip I took the "Two-day Car Control School" at the BMW driver training facility in South Carolina. I spent much of the first day in a 135i, so I was able to really evaluate the 128i versus the 135i.
My conclusion: If I had to make my purchase decision all over again, unless I planned to do a lot of really high performance track driving (in which case I'd go for the 1 Series M), I'd still buy a 128 over a 135. At low RPM's it's hard to tell the difference in torque between the two engines. When you get on it really hard, of course the 135 is faster. The 128 engine is silky-smooth and the power delivery is much more linear over the useable RMP range. Whereas the 135 is more "ballistic" - making it, in my opinion, actually somewhat harder to drive (requires more concentration to drive smoothly) under normal and moderately aggresive street conditions.
I believe that whether any given driver will prefer the 128 or the 135, really depends on what vehicle characteristrics he finds most satisfying over the long run. To me, the 128 feels light, agile, precise, fun, and sporty, yet relaxing after a long day of driving.
Since you want a manual trans, I assume you would be special-ordering your vehicle; so if you go for a 128, be sure to get the Sports Package - the seats alone are worth the extra cost - and I like the tighter suspension and better handling, even though it can be pretty harsh on very rough roads.
BTW, I highly recommend the BMW 2-day Car Control School. They will teach you to do things you may have thought were impossibe. For example, I was VERY surprised at what a 335 diesel, even without a sports package, could do in an high-speed 2-lane-change extreme evasive maneuver; and I was impressed at how well you can steer a car under maximum panic-stop ABS braking. Also, the water-covered oval skid pad is a hoot!
Last edited by 128Guy; 07-03-2011 at 01:21 PM.