If you don't modify the cardboard, I think it would break down from the elements like rain/moisture. That's one of the main reasons why most people use coroplast instead of cardboard. I did use cardboard to build my templates as I didn't want to screw up my big sheet of coroplast...
I mean just the temporary use for testing. I wouldn't leave it on for any permanent design. Just a way to see if it actually works and improves MPG and then make something more permanent. I also live in Southern Ca. where we won't have much rain now for months to come. So I could do some good test'
I'm looking for thoughts on weather I could see any improvement thanks
for small things like wheel dams it works quite well. i once made some wheeldams from card (no corrugated but the kinds that backs writing pads) and i gave that a couple of thick coats of black acrylic paint.
the mods themselves didn't work well aerodynamicslly but they did last trough quite some wetness and even stood up to some scrubbing against the ground on very uneven ground.
i've seen a few cardboads cambacks tested too so i'd say it's worth a try. dry seasons are always better especially for big things but smaller items with a little water proofing will work well for long enough to test them
just make sure all is attached well and the whole construction has enough strenght... you want to be able to give whatever you have a little beating without it comming appart right away.
Our 94 Altima has a huge chin air duct, I blocked it completely and measured a 10% reduction in overall drag at 60 mph.. I can't really equate this to gas mileage because she who must be obeyed is the primary driver and refuses to cooperate in hypermiling or even recording fuel usage..