Its just the cheap way that these cars are painted. They didnt do this for any purpose. When the car is painted, the paint runs down. A lot of cars have this, some worse than others. My M3 doesnt have this near the bottom, but it has it all over the paint to a smaller degree.

When I had my Modena 360, there was no orange peel anywhere, neither was there on my NSX.

You can get rid of it by wetsanding but its not worth it.

 

ive just noticed different cars tend to have this toward the bottom im not sure if its on purpose or a bad paint job, but ive seen it on different model cars