Hirosimez mentioned 400e is faster than most bimmers.
I do not recall saying that
The only car referenced in respect of speed was E34 535.
Also, it depends on what you mean as "fast". If it is a 0-60 or in-gear 50-80 time -then sorry, 400E does not feel that fast, as you reach and exceed that speed in no time but also without any drama. If you want lots of action and feeleing - try SAAB 9000 2.3Turbo or 9-3 Viggen - you will be sweating with both fear and sheer excitement every time the tach needle is past 2200 rpm.
If it is max speed - 150 mph is certainly fast but one should be insane to drive like that on our roads. Note: Germany and its
autobahns (where 400E & 500E are most at home) is totally different.
What amazes with 400E most - is how effortlessly, smoothly and quietly it picks up speed, any speed. To me it is a 500E Lite of a sort, more biased towards comfort and hi-speed long range cruising, rather than sheer thrills. And it fits me nicely here in Canada.
How reliable is the 400e V8 engine compare to 300e 2.8 engine?
One of the best MB efforts certainly. I do not have long term statistics for engines mechanical reliability and should rely on what service techs and forums say though, it appears the later M104s (2.8 & 3.2) are more troublesome than either earlier 3.0 M104s or M119s.
More experienced folks - please correct me if I am wrong.