I made a partial grill block out of coroplast, and have seen a slight improvement of mpg. My ultragauge says I went about 730 miles and my avg mpg was 17.5. Since I've had my grill block my avg mpg stays in the 17.9-18.1 range. And on the freeway before the block I barely ever saw over 30 mpg going 65. Now I consistently see 30-32 mpg going 65
![Big Grin](/forum/images/smilies/biggrin.gif)
I barely ever go on the freeway, so the averages are like 90-95% city driving.
I could only find white coroplast, so it kinda sticks out, I plan on spraypainting it black to look better. It's held on with thick zip-ties that go through 2 holes that are perfectly placed behind the grill, Chrysler actually made something conveniently located!
![EEK!](/forum/images/smilies/eek.gif)
I'll post some pics later.