What is the reason for all of the interest in this part of an automobile?
There are two key reasons. One is practical and the other one is cosmetic.
From a practical standpoint a vehicle moving through air sometimes acts like an airplane. That is, the air flow under a car or truck travels a slightly shorter distance than the air flow over the top of the vehicle. This difference causes a pressure differential, with the low pressure at the top of the vehicle.
This means that there is greater pressure trying to lift the car up, than keep the car on the road. The weight of the car is enough in most circumstances to overcome this tendency to lift up. However, move the car fast enough and thereby increase the air flow and interesting things can happen. Just like an airplane taking off, enough speed equals enough lift and you are air borne.
What is good for an airplane is disaster for a car. If you ever watch pictures of car races, you might see a picture of a fast moving race car suddenly lift up in its front end and sometimes completely flip upside down.
The front spoiler or lip or air dam, is designed to stop this dangerous air flow, on a race car or an exotic car which is capable of very high speeds.
The second reason these devices are added to cars is for styling. People like to feel they are driving a fast car. They want the appearance even if they will never push the car to speeds that require an aerodynamic device like this. If you look at most new cars, you will see some type of extension below the front bumper. It’s there for the design and not to hold the front end of the car down.
Since not all cars come with this look, there is now a large aftermarket which designs and builds lips, spoilers or air dams for people who want to dress up their pride and joy.
Is it all positive? No. There are a couple of things to keep in mind. First, this is additional weight on the front end of the car. It should not make a difference, but if you add a very heavy weight to the front end you can change the handling characteristics of a car. Second, you have now lowered the distance from the front end to the pavement. On a level road, there should be no problem. However, hit a dip, or a tall parking block, or even a steep driveway and you may find your front end is dragging on the ground.
The last caution is installation. Most aftermarket products like this require a certain amount of expertise to fit it correctly. If you do not have this experience, find a professional for the installation.