Components like those are designed to optimize the airflow throughout the car's body. In other words, their geometry is carefully shaped in order to make airflow with fewer turbulences and deviations as the car moves. That effort reduces the amount of power the engine needs to dedicate to overcoming that resistance, which means there will be more left for effectively developing speed or the car will need less energy to maintain a given speed.
Parallel to that, body kit components can also be designed to help with everyday issues. Splash guards, for instance, are indicated for off-road cars in order to keep water and mud from making the whole body dirty. A spare wheel cover protects it from the actions of weather, and so on. As long as you search for trusted suppliers, you will only obtain components with the best and most effective designs.
To that end, Mercteil knows that offering a long list of options is not enough. All of them are genuine, with no exception, but they are also organized with a system of filters which you can easily apply as needed. That will help you focus on the options which are perfectly appropriate for your car model. How about giving them a look at them today?