I will take Mercedes CLA 180 Blue Efficiency as example.
CLA 180 BE has Cd =0.22, but same car with label CLA 250 has Cd=0.30, to me this is huge difference because both has identical body shape.
Is it possible to reduce Cd by 8 points,if body shape keep the same, but only change this "minor" things?
Members who work with CFD can help here, how much CFD results change, for this "minor" changes, maybe you notice that during your CFD work at F1 cars?
(I allways thought tha body shape,especialy in cars, is 95% of aero job.You cant get 0.25 from brick, whatever you do.)
CLA 180 BE has this aero features:
large diffusor cover
optimized rear muffler
aero covers for spring links
cover for rear axle subframe
optimized main cover
slotted wheel house liner
optimized lower stiffener
demand controlled cooling air, using adjustable radiator shutter
optimized front apron
large area of underbody paneling and additional cladding in the center rear axle area
serrated wheel spoilers at the front and rear wheels
slotted wheel arch linings
low A-pillar shoulder
aerodynamically optimized exterior mirror housings
aerodynamically optimized rear end design (flush sitting boot lid and fins in tail lights)
aerodynamically optimized rear silencer with downstream diffuser
wheels and tires with low air resistance