Well, today I took my first trip after doing a couple of modifications.
Here's the first modification. An air dam as the car did not come with one from the factory. This is just composite garden edging purchased from Lowes. I bought a 20' roll of it. The reason why I didn't expand it out farther than this is because the radiator support that it is attached to ends at the edges of the edging, and there was nothing to secure a longer air dam to.
I also installed a makeshift warm air intake, but I am afraid it is not benefiting or hurting mileage at all. Here is the reason why.
If you look at where my finger is pointing, this is where the stock air intake gets it's air from. Not from the fender well, but from under the hood by the battery. I have noticed intake temps on the highway to be identical now as compared to what they were with the factory air box. In town, there is only a 10 degree increase in intake temps, even when sitting still with the A/C on. I am amazed there is so little difference.
So the first trip with the new modifications was 128.5 miles, used 3.211 gallons (the same gas pump where I filled up last) and averaged 40.01 mpg. This was achieved by maintaining an average of about 65 mph with the A/C off. This represents a slight increase in fuel economy compared to what I have seen before the air dam. Now I need to do a partial grill block to try to take advantage of the air dam and see if mileage goes up even more. Then I'll try adding side skirts with using the same garden edging composite material to see if I can get highway gas mileage up to around the 45 mpg mark.
Please remember, this car is an automatic so in my opinion, 45 mpg would be an ENORMOUS goal to reach considering EPA estimates highway mpg for this car at only 30 mpg.