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      10-26-2007, 12:29 PM   #85
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Good summary

Originally Posted by lucid View Post
Guys, I have lost track of the real difference of opinion in this debate. Swamp has done some detailed modeling of the 0-60 scenario with CarTest, which does seem like a fairly comprehensive and reliable simulation environment when it comes to that sort of thing. I believe he has validated the accuracy of the environment for several cars by using manufacturers' specs as parameters for the simulation and comparing the outcomes to the performance figures reported by magazines. That said, it is valid to question a simulation outcome--regardless of the comprehensiveness of the model being used--which I guess is what gbb357 is doing. For instance, my understanding is that C&D is using rolling starts in the 0-60 test. Does CarTest model that? Where does CarTest get the necessary data for modeling transmission losses, and how accurate are that data (I am not talking about the conceptual physics model that is being used to simulate the losses; I am referring to the actual parameters). Regardless, I think it is possible to say that, with some degree of confidence, an engine might be underrated if things simply do not add up in the end. Maybe the issue here is what level of confidence one can make such a statement given there might be uncertainties in the simulation model. Is that the basis of this debate? If it is, then I don't see how one can come up with a definitive answer in the absence of a larger statistical database which shows how CarTest simulation outcomes compare to reported real-world performance figures from multiple sources. Maybe the authors of CarTest have published that type of information?
A good/fair summary I think.