My first mod was the upper grill block in the photo, made from a thick hdpe plastic plant pot. The lower grill block was made from a thinner plant pot, on the sides of a 7" wide opening below the license plate, which resulted in my highest mileage to this point. The coolant temp was mostly at 199, and got up to 206 on the climbs, maybe too warm as the outside temp was only low 60's, the same for the return trip a few days later. The wind was calm during both of the trips, but the mileage was 6mpg less from the second one, maybe because the fan was on more on the hills.
I changed the lower grill block to that in the photo for my next trip, made from from the very thick plastic from an old city garbage bin. This was not as good, as the mpg were less, and the temp was in the 204 to 208 range more often. Prior to the return trip, I cut off the bottom corners, an inch under the license plate, and pulled the bottom sections inward to the grill. The splits on the return trip were still not good, but improved past the peak and the mpg was my highest coming west. I think the fan was still coming on a lot the first half of the trip, as the outside temp got up to 90.
The fan coming on can explain much of the inconsistency in my mileage.
I want to keep improving the grill blocks, gain more consistency, and get the temps down so the fan won't come on. I think the upper grill block is okay, but want to improve the lower one, and add an air dam to the bottom, or else combine them together.
