We pretty know how the M135i/M235i and the A45/CLA45 AMG stack up and the AMG's have won every performance comparison thus far. This is the first comparison with the all whee drive version of the M135i and it makes quite a difference in the acceleration. The TT-RS beats the other two fairly easily. However, the addition of all wheel drive really helps the M135i get off the line. For whatever reason the A45 AMG has a poor launch but it eventually reels in the M135i up top and passes it. It is the quicker and faster car of the two.
It is interesting that the car with the greatest displacement loses to the turbo cars with lower displacement. However, the M135i is hardly the best it can be. The N55 is not as aggressively tuned as it can be and unlike the Audi and Mercedes it does not have a dual clutch transmission. Add a DCT, a more aggressive tune, and the M135i should beat these easily. Perhaps that is what is in store for a future M2 model.
There is also a track comparison in addition to the drag race but considering the Germans use three different drivers it is not much a comparison due to the driver variables. However, the A45 AMG wins this comparison.
Skip to 2:40 for the drag race unless you like to hear German.