Table 2. cw values for vehicle modifications

Effect of

Lowering vehicle height by 30 mm.
Smooth wheel covers
Wide tires
Windows flush with exterior
Sealing body gaps
Underbody panels
Concealed headlamps
Outside rearview mirrors
Airflow through radiator and engine compartment
Brake cooling devices
Interior ventilation
Open windows
Open sunroof
Roof-mounted surfboard rack

delta cw in %

approx. -5
-1...-3
+2...+4
approx. -1
-2...-5
-1...-7
+3...+10
+2...+5
+4...+14
+2...+5
approx. +1
approx. +5
approx. +2
approx. +40

Effect of windshield slope on the cw value

(- = better, + = worse)

 

Windshield
slope

cw

delta cw in %

50 deg.
0.345
--
55 deg. 0.342 - 0.8
65 deg.
0.340 - 1.4
40 deg.
0.349 + 1.1
30 deg.
0.349 + 1.1
0 deg. 0.369 + 7.0

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