Hi,
Aerodynamics plays a part, but, as you already found out, they also play a role in protecting the Fuel, Coolant and Brake Lines.
I'm not sure which of the 4 panels you need. They are:
- Front Cover - PN# 996.504.527.02
Center Cover - PN# 996.504.043.02
Rear Cover - PN# 996.504.119.00
and simply Cover (the 'L' shaped one) - PN# 996.504.561.00
Hope this helps...
Happy Motoring!... Jim'99