got a problem with antennas fixed on my truck

i got this one (x2) fixed on my truck............
http://www.hyperlinktech.com/web/hg2409mgu.php

i saw a thing really weird ... a guy which was wardriving with a truck(im living into one too) and using an antenna really weird, in facts he used his own whole truck, so my questions are.......

1 DO YOU KNOW TUTS FOR USING THE TRUCK AS AN ANTENNA ?

2 IF ITS POSSIBLE, WHAT DO YOU THINK ABOUT POSSIBLE PERFORMANCE FOR THESE SYSTEMS ?

in facts, it's only that i want to test this thing on my own truck but i don't find anything anywhere....