[aerohead]

I've been wrapping up noodling on the HOT ROD Magazine Camaro Red Hat Project LSR, Ford Fusion 999 Hydrogen LSR , and Volkswagen Jetta Hybrid LSR cars.
* All used wiper delete
* All used mirror delete
* All were lowered
* All used narrow GOOD YEAR EAGLE racing tires
* All used the MOON Equipment, full, convex wheel covers
* Two of three used 100% grille blocks ( Jetta did not )
* Two of three used 100% belly pans ( Jetta did not )
* two of three used rear spoilers ( Jetta did not )
* All cars were allowed a 5.3% frontal area reduction ( mirrors, lowering, narrow tires)
* The apparent departure angle, from backlight-to- spoiler top, happen to match the streamlined 2013 template contour for the Camaro and Fusion
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* The Camaro went from Cd 0.467 to Cd 0.20
* The Fusion went from Cd 0.34 to Cd 0.21
* The Jetta went from Cd 0.28 to an estimated Cd 0.2706 ( reverse-engineered from Volkswagen data )
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* The Cobalt sedan SS, with high-mount rear 'wing' is published @ Cd 0.324
( I've seen no other reported Cds for the Cobalt
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* The Cobalt EcoTec LSR car used wiper delete
* The Cobalt used mirror delete
* The Cobalt is lowered
* The Cobalt used narrow GOOD YEAR EAGLE racing tires
* The Cobalt used the MOON wheel covers
* The Cobalt used a 100% grille block, except for a combustion-air inlet at the forward stagnation point
* The Cobalt used a 10-inch rear decklid extension spoiler identical to that of the Fusion
* The Cobalt would have been allowed the 5.3% frontal area reduction
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I've yet to find a 'blueprint' for the Cobalt.
Should I do so, and find that it also matches the same contour, the implication for me is that the Bonneville spoiler allows:
* altering the basic vehicle configuration to generate negative lift ( W.H. Hucho, page 281, 2nd-Edition)
* ' Additional force is obtained by positioning the rear positive pressure far back behind the rear axle... thereby producing a greater leverage about the center of gravity.' ( Hucho, page 282-3, 2nd-Edition )
* ' The attached spoiler ... provide(s) nearly the same drag and lift coefficients as raising the upper rear edge ( of the body ) [ Hucho, page 175, 2nd-Edition ]
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The spoiler constrains the flow, forcing it to follow a streamlined pathway, facilitating flow attachment, flow deceleration, pressure recovery, increased base pressure, pressure drag reduction, reduction of rear lift, and providing a robust flow environment for pilot-chute inflation/ main parachute deployment.
It's not as 'good' as just streamlined shaping of the car, but it does satisfy SCTA Rulebook body modification limitations.