Seeing a lower grill block as being the easiest and cheapest aerodynamic modification, I decided to attempt this one first. I tried this once before with auto masking tape, but the design of my bumper made it difficult and it didn't last long. I'll add a few pictures to give you an idea of what I have done.
My front bumper:
I used some black rubber wall-liner that I picked up for under $4.00 per 48''x4'' piece. Basically it's the rubber base-board material you see in office buildings and schools etc.
I shortened the rubber to fit the width of the lower grille and simply used black electrical tape to hold it in place.
Here's the finished product:
I purchased two pieces of the rubber material and a roll of black electrical tape for $8.68 and installed it in under 15 minutes. I'm not sure if it will yield any gains but I figured it was worth a try.
Suggestions appreciated
Thanks