At the urging of at least one member on another thread and after reading several threads on the forum about this, I decided to go ahead and fill in the hole in the bumper for the now-gone inter-cooler. It was about the simplest thing I have done so far. I just cut a rectangle of aluminum sheet and sandwiched it between the mesh and the license plate. This is how it looks now. Based on my reading here, I am sure this is a more efficient design than what was there before.
I am sorry I cannot report any actual numbers for mileage. I change this car too often to get a good baseline. But, it is going up continually. A year ago it was getting as low as 12 MPG in local driving. I think this last tank of local driving is going to yield around 20 based on the gas gauge. This has been extremely local, with trips as short as 5 miles to car cruises often. Today I took it on my job and drove it 50 miles total. I will begin to get better numbers here as I use it more. I am going to look into the MPG display that is possible with my fuel injection so I can have better data available.
