The 'vette looks like more of a taper than the template, both vertically and horizontally.
Volvo concept car might be "on template", definitely doesn't look like as much of a taper as the 'vette.
I expected the Phil Knox taper to be close to the template - - -
but it does not meet the outer perimeter of the cab. My guess is that there must be lots of eddies and turbulence at the cab corners.
I might put on a decal "Civic Elize MPG by BP"
Maybe model mine after this 2008 Lotus Elise:
Or the 2011 version: