I have been making these deflector prototypes since 2008 and most of them do the job but does not look professional at least to my liking.
yesterday it clicked in my head and I think I found the solution at least for use who drive with narrow tires like I have 165/65R15 at the moment. I was just looking for rubber to buy for making these deflector but picture search kept showing me rubber boots
.
Just buy some rubber boots that look like this:
Those are not actual rubber they are some EVA-Material (Ethylen-Vinyl-Acetat). they seem to be little higher in which is better for aero than normal rubber boots. But the matt look is what I needed.
There with one pair of these in size 47 costs 18.85€. estimated impact to drag is 0,02 but when I try to make them also to rear and tweak also the wheel well front lip I would estimate and hope I can lower the drag even 0,03 to 0,04.
In my car that means at 100 km/h speed or 62 mph
Cd -0,02 = 0,16 l/100km=0,24€/100km savings or ~104km/h=100km/h consumption
Cd -0,03= 0,24l/100km=0,36€/100km savings or ~106km/h=100km/h consumption
Cd -0,04= 0,32l/100km=0,48€/100km savings or ~108 km/h=100km/h consumption
Even the lowest drag reduction of 0,02 gives payback estimate that its under 10000km so one oil change interval
Cannot wait to start cutting these when they arrive.