Guy has a lot to learn about aerodynamics. He could have reduced his drag a lot better building a contraption like he did for the front for the rear of the car instead.
A teardrop shape would have been a more aerodynamic than anything with a blunt rear end would be.
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2004 S60R - 350+ HP, AWD, Custom FMIC & Exhaust, Active Suspension & A Big Set Of Brembos
Crazy Camber, Stretch & Poke; its the new triple-stack-bleacher-wing ricer fad that's all the rage nowadays, lol