Quote:
Originally Posted by NHB
Many models are similar in that sense and it doesn't make any sense at all to offer inferior aero parts in more expensive car. I doubt that Mercedes has engineered downforce in those models at least if we don't count AMG model. This increase of Cd value hand in hand can be seen in many other cars. It is actually the Newton's forgotten law.
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Inferior? I don't believe that any model has "inferior" aero parts. They are just aero parts which have different goals. Aero parts designed for FE aren't inferior to those designed for downforce/venting. Just as those designed for down force/venting aren't inferior to ones designed for FE.
Why would we not include the AMG? You listed it as an example, it should be included. If we don't include the AMG then we shouldn't include the BlueEFFICIENCY Edition since it has changes made specifically for aero like the AMG does. IF we do that, we are only looking at a .04 increase in CD between the CLA 180 FWD (90kw) and the CLA250 4Matic AWD (155kw) models. And from what I gather, the underbody is different due to having a drive shaft and driven rear wheels which would impact drag compared to the FWD version... Of course I can't find comparison pictures for the two underbodies to see if this is true. I also assume AWD would lead to more heat/venting/drag than the FWD version.. Another factor that isn't taken into consideration when looking at CD relative to engine output.
Quote:
0,22 CLA 180 BlueEFFICIENCY Edition 90 kW (skinny tires)
0,25 CLA 180 90 kW
0,29 CLA 250 4MATIC 155 kW
0,32 CLA 45 AMG 4MATIC 265 kW
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And I agree, it can be seen hand in hand in other cars... Just as ground effects, diffuser, exhaust, underbody, airdam differences can be seen in many of those cars. I understand the science and theories behind heat exchange and drag... I don't deny that it exists. But I'm a hands on kind of person, lets actually look at some differences in models.
CLA 180:
Front end specific FE based aero designs, wheels with lower drag
AMG 4MATIC
Massive air intakes with functional winglets, splitter, and non optimized front apron, drag creating 18" 5 spoke wheels
Again, not saying it isn't heat exchange and "tires" that cause the difference in CD... I just find it hard to believe that those are the biggest causes when I look at the differences in design on these particular vehicles side by side. Especially after reading the projects on this site where people have done simple tweaks to decrease CD for better FE. Tweaks that are the opposite of what Mercedes did on the AMG (bigger intake/vents and larger open tires for example).
Sorry to the original poster for kind of high jacking this thread... I still stand by the generation of down force for application of power and safety with handling at speed
~C