Phil Knox Darko Wind Tunnel video
 

https://www.youtube.com/watch?v=Z2FU9Sm2qLY

Phil Knox uploaded his video last week of the Darko Wind Tunnel testing he did last September 2017. I am sure he will post it soon with comments of his own but I just wanted to throw it up here at ecomodder so folks can get a look at it.

I skipped around a bit on the video. Certainly does seem to practice what he preaches - air attachment.

Looking good

What number did the "Template" model do?

Something hanging from the back of the truck's bed cover is barely moving in the wind. (@ about 13:30)... not a whole lotta turbulence back there.

Spirit of Ecomodder was as solid as a rock. The Dodge was rocking and buffeting at the same speed.

Template numbers
 

*the 3-run average for the 'long-tail' was Cd 0.1209.
*for the bob-tail it was Cd 0.1487.

hanging from the back
 

That's the ammo box latch portion for Spirit.The other half is part of the new tail,which I couldn't finish in time for the trip.
Below the latch,you may see a glimpse of the 'REMOVE BEFORE FLIGHT' flag on the boat tail swing-away mount, 3/8-inch quick-release pin,blowing around in the wake turbulence.

numbers for Spirit-II
 

As an 'electric' truck,with a camera system,Spirit measured Cd 0.297.
As-driven,without the Viper windshield,gap-filler,with mirrors,and an open cooling system,she came in at Cd 0.345,same as a ZO6 Corvette.
In 2014,with the old boat tail and more belly pan,she measured as low as Cd 0.244.If measured at the A2 Wind Tunnel,it might have registered Cd 0.219.
The reason being,that Gary DeLassus' Prius-III measured Cd 0.285 at DARKO,vs Cd 0.26 at the A2.
If the same relationship were to hold true with Spirit,then we might not be surprised to see the lower number in North Carolina.
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Spirit-II's best mpg on the trip was 37-mpg at 55-mph,between Ogden,Utah and Fernley,Nevada.
Spirit has never returned over 30-mpg without a boat tail,so I'm pretty encouraged about the upcoming 2020 Spirit-III trip,when she'll have all the whistles and bells.

So a full scale electric car could be expected to do at most this good. Or better.