@CD
So why would rounding the front NOT decrease the overall drag? Pretty much in any sub-sonic application a rounded approach will allow air to slip around the object far better than a flat face.
Maybe it could create unwanted flow separation on the sides but that would definitely already be there.
Aerospaceweb.org | Ask Us - Drag of Cylinders & Cones
And I did the front fiberglass part (originally there was an air gap between the rounded word part and the hood- that was hardly a 1 mpg improvement) and pizza rims on my tires both at the same time and my mpg went from 31-36 to now I have at 38.7 tank and a 41 mpg tank. Pizza Rims were probably only about 25% of the gains because other people would see 10% gains with terribly unaerodynamic rims.
But this is good news. It looks like if I do the back I'll get some huge improvements.
I also have a panoramic mirror that relies on the back not being obstructed... That means I would have to make the rear panel out of bended plexiglass to still have the benefit of essentially no mirrors. A little bit of a curve might be a tad better than a flat panel.