[aerohead]

I ran an energy balance for the ZEVO, based on the reported range performance for:
63-mph, 8,800-lb test weight, approx. 69.6024-square-feet frontal area ( 6.4662 meters-sq. ), 178-kWh 'useable' ( 5.2811-gallons gasoline equivalency ), 100% SOC-to-Zero% SOC, 360-miles range, 68.1674-mpg-e, 494.444 Wh/mi., 31,149.999-Watts/hour, 41.7728- bhp-e, @ 95% BTE-e, 39.6841-hp Road Load, best-case Cfrr= 0.0055 lb/lb.
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Using the test weight, Cfrr, and road speed, I got a Rolling-Resistance horsepower requirement of 8.1312-hp.
Subtracting this from the road load leaves 31.5529-hp left over to satisfy the road aero power requirement.
Using standard air, @ rho= 0.002378 slugs, 92.4-feet/second air velocity, 550-lb-ft/sec ( horsepower-work conversion factor ),the stated frontal area, the only drag coefficient which can satisfy the energy balance is Cd 0.2658, for a CdA 18.501-sq-ft ( 1.7188 meters-sq ).
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Conditions/caveats:
* Steady 63-mph travel
* Calm
* Dry road
* Smooth concrete road
* Flat road
* Air-conditioning 'OFF', 'shutters' closed
* 100% belly pan
* Flush glazings
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GM's website for the Brightdrop ZEVO 600 provides very little pertinent data, necessary for a 'proper' analysis of the vehicle.
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A 20% reduction in wake area would yield Cd 0.21265, an 18.88% increase in range ( 428-miles ), @ 415.8 Wh/mi..