Originally Posted by Nick the Greek
Where do you get 15% loss from? BMW are usually quite conservative on quoted power so a figure closer to 400 bhp for an engine quoted at 381 bhp would not be unreasonable. Look at the dyno figures for the new N20 engine conservatively rated at 242 bhp.
Yes agree that many BMW engines are under rated but i dont think this is one of them, I would say its the opposite to be honest based on the performance tests ive seen. The 15% drivetrain loss was taken from another thread here were a US member has his 550i on a dyno, im not sure on how accurate that figure is though.
Ill try and find them but there was a test between a M550d vs A6 BiTDI and the BMW was barely any quicker than the Audi. Also in another test between a 535d, M550d and Alpina D5, I was surprised in the little performance the M550d had over the other two and I think in a couple of tests the D5 was quicker.
Looking at the price difference between a M550d and 550i in Germany, i find it tough to justify why you would go for the M550d.