Reg Edwards wrote:
. . .
I've often thought of modelling a mobile loaded whip in a computer
program. Input data would include body dimensions and height above
ground. With a lot of patience you could do it with an EZNEC type of
program.

Many people have done it with EZNEC. At HF, all that's necessary is a
pretty crude outline, except in the close vicinity of the antenna where
currents can change more rapidly. At VHF and above a much finer wire
grid model is necessary. But as others have pointed out, a lot of modern
cars aren't covered by a solid metal shell. So it might be difficult for
these cars to figure out just what external and internal metallic parts
will be carrying the current and therefore need to be included in the model.

Roy Lewallen, W7EL