"now, fins do help... you see, when the car is travleing at high speeds, the air tends to go under the car and lift it up, and a decent sized fin, along with a bumper or whatever it is...a body kit... can help it stay on the ground. "
Considering that Honda Civics and Ford Probes and the like are front-wheel drive (not to mention incapable of reaching speeds high enough for the fin to make much of a difference), if those fins were there for aerodynamic reasons they'd also be putting a fin on the front.
No, they're just slapping 'em on there because they have poor taste in asthetics. Any car (besides a late '60's Daytona/Superbird) with a huge fin = stupid.
J_A_B