SPA XC90 Drag Coefficient Discrepancy

awy · Post by **awy** » 05 Sep 2023, 12:02

Looking at the reporting/literature on the SPA xc90, the drag coefficient was reported at 0.30 early on, but this was altered to 0.33 after 2017 or so. Does anyone know the cause of this discrepancy and whether any material changes to the design caused it, or was it just updated testing/CFD meshing etc?

Post by **volvolugnut** » 05 Sep 2023, 12:19

Wikipedia has an article including CD for many recent car and SUV models, but does not list the XC90. Discussion in the article mentions the added drag of roof racks. If the XC90 had a roof rack become standard in later years, this might explain the increase.
volvolugnut

awy · Post by **awy** » 05 Sep 2023, 20:43

hm don't think the roof rack is standard, although it could explain the size of the difference.

i'm thinking besides the rack, the big source of discrepancy would be wheels. the new EX90 with aero grille block and aero wheels got a 0.29, so 0.30 with nearly the same shape but not these two mods seems rather difficult to achieve.

Post by **BlackBart** » 06 Sep 2023, 10:32

Someone forgot to roll the windows up during the test.....