Partial Grill Block
 

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 :D 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:
I'll post some pics later.

Ya, I had to take down my partial grille block for the warmer months. But then I've got a mountain to climb at the end of a 30 mile trip...

I'd be interested to see the pictures when you get it re-done. : )