[AeroMcAeroFace]

It is a very interesting paper actually.

Downwards roof slope gives huge lift, 20 degree downwards slope is higher lift and higher drag than 15 degree downwards.

"little data is available on the effects of streamlined tails on non-axisymmetric bodies, whether representative of road vehicles or not" Presumably they need to "read between the lines" more despite reading the same books template enthusiasts have.

Tapering is good, but cannot be done arbitrarily is the main theme of the paper. Angles that work on the roof don't necessarily work on the sides, and vice versa.

I̶f̶ ̶y̶o̶u̶ ̶a̶r̶e̶ ̶g̶o̶i̶n̶g̶ ̶t̶o̶ ̶e̶x̶t̶e̶n̶d̶ ̶y̶o̶u̶r̶ ̶c̶a̶r̶,̶ ̶d̶o̶n̶'̶t̶ ̶e̶x̶p̶e̶c̶t̶ ̶a̶ ̶s̶p̶e̶c̶i̶f̶i̶c̶ ̶a̶n̶g̶l̶e̶,̶ ̶s̶h̶a̶p̶e̶ ̶o̶r̶ ̶p̶r̶o̶f̶i̶l̶e̶ ̶t̶o̶ ̶b̶e̶ ̶o̶p̶t̶i̶m̶a̶l̶.̶

If you are going to extend your car, a profile that works for someone else may not work on your car.