BMW has helped the driving dynamics of the 306 hp M135i, which is somewhat banal by M standards, with a technology update. Does the follow-up work?
We're going to try that without the usual obituary for the predecessor and instead simply accept the BMW M135i as what it has become in the meantime: a conventionally built, robustly seasoned compact sports car, which, however, has always changed in the end harder to fulfill what its initial promises. Because M doesn't stand for mediocrity.
So that we understand each other correctly, this is not about the engine. In contrast to its predecessor, it only has four cylinders, installed transversely and has a comparatively brittle charisma, but it comes super snappy with the boost pressure, revs powerfully and with its 306 hp is exactly where the music is playing in its class.
However, the drive lacks this crucial development step to the top. The crux? Is related to the unfavorable balance and the structure of the all-wheel drive system, which integrates the rear axle into the power flow according to the Haldex principle. Depending on the situation, with a maximum of 50 percent of the 450 Nm, but either completely or not at all. In the meantime, however, parts from the competition have so-called torque splitters at work, which divide the drive torque rear-axle and can thus direct it to the rear wheels - via two clutches, in favor of a turning effect in the steering direction.
And that's exactly what the BMW can't do, which tastes a bit bitter in that a) you know what such torque split systems do with a VW Golf R, for example; and b) you have to keep in mind that the simple M135i costs almost 2,000 euros more.
Get the best out of it
Just what to do? One variant would be to sit out the situation in order to attack again at some point with the successor. But because M also stands for doers, the decision was made to tackle the problem directly. The decisive factor for this development supplement was not only the manageable results in various performance tests, but also the data from the customer vehicles. They are recorded anonymously as part of the services and, according to BMW, prove that the M135i driver demands the maximum potential of his compact sports car as often as drivers of an M3 or M4. And because, as you can hear, you weren't completely satisfied with this potential yourself, we're sitting in this screaming yellow M135i today, which - as it's officially called - has had a driving dynamics update.
What's behind it? To put it bluntly: a kind of two-stage plan to get out of the misery. On the one hand, all the relevant characteristic curves have been tightened: all-wheel drive and wheel slip limitation now work more aggressively, the connection between the accelerator pedal and the engine has been tightened, the recalibrated steering lets the 1.525 kilograms more comfortably in the hand at high speeds. In addition, there's a helping of the ears: rough roaring when turning the throttle, dull exhaust thumping when you let off the gas - each with the friendly support of the audio system.
On the other hand, the standard M sports suspension got to the heart of the matter: The negative camber of the front axle was increased by 25 percent, and firmer bearings for trailing arms and wishbones are also used on the rear axle, which increase camber rigidity by around 30 percent. effect of the whole? Clearly! It's not as if the 1 Series hasn't been motivated to date, it's just that it lacked the ability to put this intention on the road. And above all: around the corner. Thanks to the workout, he now develops significantly more traction on the chain of command. Or to put it another way: the pudding in the musculature, of which we were often told before, has hardened a good deal: instead of buckling under sharper commands, the kinematics counteract it with a bang; the steering responds much more precisely around the central position; and even if the rear axle is still the tamest that has ever been in an M model, you can suddenly feel an effort to actively cooperate in the curve.
Tight, but never rough
It's not only convincing that the BMW M135i presses into the lateral dynamics with more bite, but above all the fact that it doesn't degenerate into a lout. Of course, this is a sports model and of course you can feel it. But even with the optional 19-inch wheels, which give the movement sequences a little more contour, all edges in the road remain round. No rumble, no sidesteps. Top!
In any case, the optional alternative is not a necessary one: the two-stage adaptive suspension in comfort mode takes some of the tension out of the context, but since the axle geometry and bearing remained unchanged here, it seems spongy in the sports program than the mechanical solution.
Admittedly, all of this sounds like peace, driving pleasure and pancakes. And within the scope of the technical possibilities, that is actually what is meant. However, one catch remains: the brakes, which were only given a new saddle colour, but not revised in terms of their rather moderate condition - at least if you take the Hockenheimring as a benchmark.