Yeah - damn Diamond for lying to us about real performance! Now if you take Piper or Cessna or Robin or Socata or any of the other plain vanilla manufacturers they never sold us a pig, and they haven't kept at it for the past 40 years either...
No, I don't work for Diamond and I was equally disappointed when the DA42 didn't deliver on its promise. But I recently learned why that is the case, and it makes me all the more optimistic that we will zoom in our 42s in the not too distant future!
A friend who is connected told me about the first trial with the new 2.0 diesel that incidently wasn't strangled at 135 hp but delivered the certified 155...
The DA42 chase pilot firewalled his engines to keep up with the DA40 and couldn't!!
Regarding build quality I find that our 42 feels and looks better than our first 40, but we recently received a new 40 and I have yet to compare. Although I must say quality of certain details is not what you would expect in a 450-500000 EUR airplane. Diamond need to find a better supplier for the chrome plated stuff.