[tyronasauras]

Finally reached my milestone of over 30 mpg with my 4200#, V8, automatic 02 Grand Marquis. It has taken just about a year to get there. Of course this was a highway only 200 plus mule test trip to pick up my mother, but half of it was with her and her ton of baggage, so an extra 400#. Nice 50 degree weather here in Michigan today, so that helped. IAT was 125 to 130F @ the throttle body. Target speed was 65mph.

Yesterday I finally installed the coroplast wheel covers. I used some 3/8" thick stuff that I scavenged for free from a sign. It fit perfectly, 17" diameter fit the "16" wheel and stuck out maybe 1/16". They weighed 2.4# for all 4. I removed the stock center caps, 1.0#, so a net weight increase of 1.4#. I secured them with 3 heavy duty Zip ties wrapped around the spokes, thru a slot in the cover and retained with the end of a second zip tie. I made the slots with a hot jig saw blade and filed to clean it up. I used valve stem extensions through a hole that I finished with a grommet. I painted the white coroplast "aluminum". I notched the cover a bit on the backside to clear a couple wheel weights and added about a 2" piece of "Dynamat" slightly offset to the center to balance the grommet and valve stem extension.

I haven't been able to find any Panthers getting over 30mpg and averaging over 26mpg in the summer and still over 25 lifetime.

I didn't think the covers would help that much, but it coasted much further, over 20% further on the flat. On some familiar small hills where the car would coast and slow, the car was now accelerating. I think the wheel well mods and partial rear skirt had little effect until I added the covers. The stock wheel face section was about 2" inset from the outside of the rim.

Thanks to everyone here for all the help and information.