Lunarhighway:
* Maybe corrugated plastic is not the right material for you. Have you tried harder plastics like ABS or polyvinyls? That's what I'm using. Those flex but are pretty hard. Also can be heat shaped and come in black so no painting required. Once scratched or dulled, they look stock.
* To attach, have you tried to screw them onto the plastic lining in the wheel well (if your car has that)? That can be drilled without causing rust.

My CR-V has a high clearance (8"/20cm), so an air dam would add a lot of frontal surface, which is why I was hoping narrower wheel deflectors would help MPG. Since this is a week-end outing vehicle (highway/big cargo/light offroad), I care most for high-MPG on highway.

I am not sure where to go next:
- Re-measure
- Remove the front wheel air deflectors
- Re-measure
=> Make a design call (maybe narrower deflector like other stock designs)
- Re-measure

I also want to do underbody work:
I bought a long rubber runner I want to attach to smooth the underbody and soundproof. The gas tank sticks out like a brick, and the rear bumper has a big hole.
I am also considering getting air foils like air tabs for the back of the SUV, and maybe for the front on the hood. That would require wind testing :\
... Well those are off topic here.

What are the definitive test results for all of you who've put air deflectors?

on the vectra i used the lids of two spindles of CD-r's just cut the top of and trough the side and unrolled them and than screwed to the plastic liners of the front wheels, the front of the rear wheel arches however is all metal (wich is the spot where a lot of these cars rusted beyond saveing...)

here's the front deflectors on the vec
https://www.fuelly.com/attachments/fo...ce509e4ddf.jpg
along with the test untertray
https://www.fuelly.com/attachments/fo...735168ede4.jpg
gave them a shot of black paint form the back, and since they're transparent that gives the font a shiny black look that can't be sandblasted of as happened on the kadett.

they don't shield much of the tire but they do keep air away from the suspenttion link and the wheel well cavity, wich i think might be more important.

i'm considering enlarging them as they might work better if they where bigger, but i think i'll refine my undertray first. also too small will still save gas (or do nothing at wosed.... to big will waste gas as it adds drag over stock!)

do you have some pictures of what you made? would be nice to see , even if you think they're not right

For those with deflectors and reading this:

Anybody have significant MPG gains measured from their deflectors? If so what do they look like and what do they really shield?