BMW证实，M3 M4最具特色的碳纤维传动轴，将会改成钢制传动轴
原因与排放法规有关
BMW将来会在排气系统加上一个微粒过滤器，而碳纤维传动轴所占据的空间比较大
所以就要换成比较不占空间的钢制传动轴
虽然空间减少了，但重量却会增加
这些增加的重量可能就必须要从其他地方偷回来(或者就直接变重了...)
不过BMW还是不免要强调一下性能与品质是不会因此而改变的
M-Power 爱好者表示：
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https://goo.gl/TknKjR
BMW M3 and M4 to lose carbon fiber driveshafts
One of the current BMW M3 and M4's most distinctive features is their
carbon fiber driveshafts. Sadly, the two BMW performance cars will become
a little more mundane in the future, as the company announced it will
transition the cars to steel driveshafts. The reason has to do with
emissions.
BMW will begin adding a particulate filter to the exhaust system at some
point in the future to stay compliant with stiffening emissions
regulations. Carbon fiber driveshafts have a larger diameter and
therefore take up too much space under the car. The "M-specific
high-performance" steel driveshaft being used in its place is narrower
enough to work.
BMW says that "the superlative performance and handling qualities" won't
change with the use of the new driveshaft. We suspect that discerning
drivers may notice a slight difference. Not only will steel add to the
car's overall weight (however little), it will also represent more mass
for the engine to move. This could mean the engine will be slightly less
eager to rev. Of course, BMW could compensate for this by shedding weight
elsewhere, possibly with a lighter flywheel or half-shafts.
Either way, though, this change still makes those M3 and M4 models
produced in November 2017 and thereafter less special than those made
before.
According to BMW, "for production-related reasons, this pre-enabling (of
the new driveshaft for future emissions equipment) needs to be carried
out universally." Presumably, this includes the United States, but as the
announcement was made by BMW's global headquarters, we reached out to
BMW's American office to see if the changes will indeed affect US-spec
M3s and M4s. Indeed, according to a BMW spokesperson, the U.S.-spec M3s
and M4s will feature this change.