These louvers are usually placed just behind the passenger windows. They are more for style than substance, and are often used on sports cars and sleeker vehicles for a stylistic effect. Think flashy cars from the 80's and that's the look you get with side louvers.
Hood Louvers
Jeeps than tend to run a little hotter than smaller sedans. They act like vents in the hood of the car helping the engine run at a safer temperature.
