[aerohead]

Using Cd 0.312, an estimated Af 28.5 sq-ft ( SIEMENS Solid Edge CAD ), 3,880- lb test weight, and 200-hp, compared to observed power consumption:
1) BOLT's drag-limited top speed = 149-mph.
2) BOLT's energy consumption @ 149-mph = 989.13 Watt-Hours/ mile.
3) BOLT's EPA range at 149-mph = 65.7-miles.
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According to MOTORTREND, August 2017, page-97, the 2017 BMW 530i, with turbo-4 cylinder, 19" wheels, and EPA 4,186-lb test weight, consumes the same amount of energy ( 990 Wh/mi ) at 70-mph, as the BOLT does at 149-mph.
This has to do with the 'brake thermal efficiency' ( BTE ) of the BMW's ICE engine, compared to the ' brake thermal efficiency-equivalency' ( BTE-e ) of the BOLT's electric motor.