Compare aerodynmics of two cars

[Jurgen M]

Mercedes CLA has Cd =0.22(180 Blue Efficiency) and Cd=0.23(180).
CLS C218 has 0.26, but CLS has wide tires, no flat bottom and other aero features like CLA.

aero features of CLA:
https://www.car-engineer.com/mercedes-cla-is-the-most-aerodynamic-production-car-of-the-world/

If we compare just body shape ,do you think CLS has better Cd from CLA, for example if we put narrow tires, flat bottom etc maybe CLS will have even better Cd then CLA?

I ask this because CLA is short, rear roofline looks to stubby, rear window+trunk slope is too steep,this can cause flow separation or too steep slope induce low pressure at rear window+trunk.

CLS is longer, more streamlined siluetthe,rear end slope is not so steep.

 

[Lnewqban]

...
If we compare just body shape ,do you think CLS has better Cd from CLA, for example if we put narrow tires, flat bottom etc maybe CLS will have even better Cd then CLA?

I ask this because CLA is short, rear roofline looks to stubby, rear window+trunk slope is too steep,this can cause flow separation or too steep slope induce low pressure at rear window+trunk.

CLS is longer, more streamlined siluetthe,rear end slope is not so steep.

Modifying the CLS C218 car, you could reduce the factory's Cd.

1) The CLS has wide tires because it weights around 1950 kgf, compared to the 1540 kgf of the CA.
2) It also has a frontal footprint area about 4% bigger than the CA.
3) Being longer, it has more drag caused only by skin friction.

Because those three factors mentioned above only, it will still use more fuel after you improve its Cd to match the CA's Cd of 0.22.

 

[Jurgen M]

Modifying the CLS C218 car, you could reduce the factory's Cd.

1) The CLS has wide tires because it weights around 1950 kgf, compared to the 1540 kgf of the CA.
2) It also has a frontal footprint area about 4% bigger than the CA.
3) Being longer, it has more drag caused only by skin friction.

Because those three factors mentioned above only, it will still use more fuel after you improve its Cd to match the CA's Cd of 0.22.

I mean if we compare only car body, which will have better Cd..