SCANS: M3-M4 review from European Car

[Paul-Bracq-BMW]

Enjoy the read!

[Tha Baron]

Thanks for posting

[Sir Loin]

Yhanks for posting the scan. A few interesting points:

On the turbo engine:

The engine has been fitted with what BMW calls its third-generation tubocharges. Two single-scroll units were designed to work with the 7600rpm rev limit, forming part of the company's new high-revving turbo engine philosophy. They don't see why a turbo motor must have a narrow powerband, although getting turbos that are small enough to be lag-free, yet able to provide so much power up to the rev limt is quite an achievement.

The power supply should be consistent because a great deal of effort went into engine cooling. It uses a water-cooled intecooler and has five radiators behind the front bumper to control operating temperatures.

On the exhaust:

A new exhaust system was designed that not only saves weight but also uses a flap system to essentially bypass the rear muffler. Whether this gains power is unlikely with four catalytic converters upstream (the important ones are nearest the engine, with two additional cats under the car, required by US law, although there was a suggestion a new car could run without them for several years and still comply with most emissions regularions...).

The exhaust flaps open when certain criteria are met for throttle position, engine speed and load. At this point, the sound takes a nasty turn, gaining significant bass and menace. It might put a few exhaust makers out of business because it sounds that good. At speed on the fast straight at Portimao, you wouldn't imagine it could be improved.

The problem is that when an enthusiast learns that the sound is augmented, you tend to assume it's because the mechanical noise is insufficient or unappealing. As we said, this is far from the truth - the turbo-six sounds amazing - and the augmentation does give feedback at lower speeds. It's simply the perception that this shouldn't be necessary that undermines what amounts to good execution or a relatively new concept.