So yesterday I decided to cover the upper grille on the Corsica with masking tape, to see if it made any noticeable aerodynamic improvement. I figure simply taping over the grille is the easiest way to check before doing anything permanent. I also wanted to find out how hot the coolant would get.
On a 170 mile trip across the state (despite fierce crosswinds) I found that coasting times were significantly extended. There were many hills that I was able to coast down and not lose speed, some even accelerating, where I couldn't before. Level-terrain MPG might have been noticeably improved by about 2 MPG, but it was difficult to tell with the winds.
The only real noticeable difference in coolant temp was that it maintained 195 instead of 190 for the whole trip, although it was unusually warm (85 degrees), which might have influenced that as well. I don't think the temp went above 205 for the whole trip, the fan never came on.
I have to say that I am quite impressed by this mod. There was noticeable aerodynamic gain, and coolant temp didn't seem to be affected much. In fact, I could probably block off some of the lower grille as well. I even kind of like the new aesthetic value of the grill block, kind of gives the ol' girl a sportier look
. Now I'll just have to look into a more permanent solution for this fix. I've never used any of that coroplast stuff mentioned on here, so I'll be looking into that when I find the time.
Happy hypermiling!