Quote:
Originally Posted by Red Bread
My M Coupe was a Z3 E36/8 with a naturally aspirated, 3.2L I6. Here's something surprising:
E36/8 - cd of 0.37
E82 - cd of 0.31
E84 - cd of 0.32 - 0.34 depending on tires and trim
Interestingly, the much larger F25 X3 is also listed as 0.34 drag coefficient.
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It's important to note that Cd is related to the shape of the vehicle. not necessarily the size. You also have to consider frontal area. Drag coefficient times frontal area equals drag area. So a small vehicle with a high Cd could have the same drag area as a large vehicle with a low Cd, and it's really the drag area that determines the "total drag".
It's quite possible for a large vehicle to have a lower Cd than a small vehicle (though most large vehicles happen to be kind of boxy and many small vehicles are aerodynamically shaped.)