In my mini quest of making my Mirage get better fuel economy I went ahead and did a few more mods. Mainly grille block, front underbelly pan, and shaved off a good bit of weight from the car.
I finally went ahead and put an underbelly pan under the front bumper/engine and I also put a grille block and filled in the foglight ports with great stuff foam (not quite finished with it) These were very quick and easy mods to do but I'm sure it'll make a difference in gas mileage.
I did the front underbelly pan using the pan I had left over from my 1997 Mercedes S420 S class. With some slight modifications I was able to make it fit. I used some heavy duty 24" zip ties to secure it in place. It is secured very tightly. I honestly never planned on doing this particular mod but since I had this pan laying around I figured why not. I don't know what material Mercedes used for the pan but it is very resilient and featherweight. Best of all it's a free mod.
washed the pan.
Aerodynamically dirty before photo:
Another aerodynamically dirty photo:
Aerodynamically clean now: (oil drops you see are not from this car)
Another angle:
Last but not least I went ahead with a crude grille block using polystyrene lighting panel. If all goes well I plan on replacing it with a more permanent solution like coroplast. As you can see I used great foam for the foglight ports. I plan on spraying more and evening it out with the bumper in the near future.
I also shaved off even more weight from the car by removing passenger seat, trunk carpeting and board, and the spare tire and hydraulic jack. Before this mod I replaced the heavy 13" steel wheels with 13" light weight alloys and a lighter weight exhaust. Stock CURB weight for the 97' DE coupe was 2171 lbs, now I estimate curb weight is 2,08X lbs.
I was able to achieve 41 mpg last fill up with tires at 35psi, a lot of highway driving with mixed stop and go, A/C on, couple friends in the car half of the time.
Now with these other mods I've done I'm hoping to get 45mpg with A/C on if I do mostly highway again with myself. If I turn A/C off and inflate my tires to max tire PSI I think I can get 50mpg. Maybe even more if I turn off my engine whenever I stop, install a boat tail/kamm back, rear wheel skirt etc... but I don't think I'll go that far.