[renault_megane_dci]

Originally Posted by johnlvs2run

60.6 ~
foam sheet, perpendicular to the ground, curving around to the sides;
55.9 ~
old plant pot plastic bumper cover, slanting slightly under, curving around to sides;
55.0 ~
slant back plastic bumper, 3" more forward at the bottom, curving to the wheels.

Based on my highest three trips, a perpendicular bumper shape, no lower than the regular bumper, has resulted in much better mpg than either slant back or slant under. I'm not sure why this is, other than perhaps getting the air to the side of the car as quickly as possible is more important than having a sharp angle that directs it over the hood. I'm going to experiment with this in a couple of days, which might mean trimming the plastic a bit more.

Could you sketch or pic the three different solutions in a single post ?