Tonneau Covers. Snap on vs. fiberglass

2 things here, first which is going to work better for my 99 Tacoma. The tonneau cover with snaps or putting a fiberglass cover. Second has anyone that has installed a tonneau cover noticed any difference in gas mileage as some magazines have reported. I have heard that your bed needs to be at least 8 feet to make a difference due to the areo dynamics in order to make a noticeable difference and imporve gas mileage.

Either one is going to work fine. They make both for the Taco. The snap on doesn't, in my opinion, look as good. But it is easily unsnapped to carry big loads if needed. It also won't hold up to the elements as well as a fiberglass one will over time.

Fiberglass will last just about forever. At least as long as your truck will, and probably longer. They also look better. They give the truck a finished look. They cost more though. And are not as easily removed for bigger loads. Some are not removable at all unless you unbolt them completely.

I can't say anything for mileage. My fiberglass lid is still being shipped.

Depends what you need it for. I have to take my cover frequently, and I have no place to store it, so a fabric cover works best for me (most just roll up and tie against the back of the cab). If there was any aerodynamic gains to be had, it was slight. I bought it mostly to keep salt and debris out of the bed when I'm not using it.

It is not 100% water proof and it makes some noise as you drive (but I've always though that was part of the fun of having a truck; if I wanted quite I'd drive a car). I learned quickly not to leave it off on a cold night (it'll shrink so much you'll have a heck of time putting it back on). If you keep them patched and coated with armor-all, they will last several years (though definitely not as long as a 'glass cover)

Fabric covers are not secure. I don't keep anything in back of any value, so I'm not too concerned. I wouldn’t put a tailgate lock on a truck with a fabric cover, as some idiot will just take a knife, cut up your cover and steal your stuff anyway.

I know GMC did a wind tunnel study on a Sonoma they raced at Bonneville in late eighties/early nineties. They found the most aerodynamic setup was a half cover over the rear of the bed only (with an open front half). It looked a little strange, but they set a record for their class that year. This was also on the boxier truck, so that may not apply to a more rounded vehicle (such as the Tacoma).