did a photoshop pixel count to find my frontal area and the value comes pretty close to the W x H x.81 method, although it turns out the data for my car did not included the width of the mirrors, just the body.
so here it goes:
vectra A (hatchback) 1988  1995
widthmirrors (carfolio)
1700mm  66.9inch
width+mirrors (photoshop calculation)
1945mm  76.57inch
height (carfolio)
1397mm  55inch
frontal area (photoshop calculation)
1,92 mē  20,66sq.ft
Cd
0.29 (carfolio .etc)
CdA (calculated)
0,5568 CdA mē  5,99 CdA sq.ft
