[lunarhighway]

mercedes lists the Cd value for different trim versions of the same model and the Cd values sometimes varry by 0.05 for visually identical cars, the lower spec models usually do better Cd wise.
larger tires and larges engines, wich allow for less grillblocking will raise the Cd

the opel calibra for example with a 0.26Cd only achieved this value on the 8v models where others had a 0.29Cd due to larger tires and an open top grill wich was blocked