Tonneaus covers - mileage? waterproof?

I am looking at hard tri-fold tonneaus comvers and would like to hear opinions on gas mileage improvement as most of the literature claims this. Also, is your tri-fold actually waterproof?

Thanks
thumpertx

 

No manufacturer guarantees their cover to be water proof. Certainly some designs do better than others. Small amounts of water is absolutely normal.

Mileage from a tonneau is another stretch. How do you drive, are you towing, whats the weather, vehicle maintenance, etc can all impact that. IIRC, Mythbusters did some tests and found a variance of a few tenths of a mile gain.

 

My extang trifecta is about 98% waterproof, not sure on the mileage improvements

 

My Advantage tri fold doesn't even leak going through the carwash. Don't know about the effect on mileage though.

 

according to results by mythbusters the tailgate net provides most mpg gain

 

My Extang Express cover is really easy to install and holds up to car washes with no leaking. I did put a thicker weatherseal at the front to keep out water. I also had to modify the mounting rail to allow use of the rail tie-downs.

 

"Water resistant" is usually the terminology used. I saw zero gain or loss of mpg with mine.

 

my extang trifold leak like crazy... the weather stripping are garbage, need to change them every 6 month look like