AR1.com has maintained that Honda's struggles on street and road courses are due to the fact that their Butt Bumpers are closed off whereas Chevy's are open. We also show you the back of all the World Endurance Prototypes that have similar appendages behind the rear wheels. Why? Because air flowing off and around the rear tires is significant enough that it causes a drag on the car if blocked off. See how all the other designers do it except for Honda, which are getting their lunch eaten in IndyCar.
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| Chevy – wide open so air flows through |
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| Original Dallara – wide open so air flows through |
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| Porsche 919 WEC – wide open so air flows through |
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| Audi R18 WEC – wide open so air flows through |
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| Toyota WEC – wide open so air flows through |
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| Honda – closed off so they are effectively towing a parachute around the track. And IndyCar would not let Honda modify their short oval and road course package, thereby locking in Chevy's advantage. Brian Barnhart used to work for Roger Penske – owner of Ilmor Chevy. |
