Throttle Controllers?
 

I was thinking about buying an ETC throttle controller and using it on eco mode. Anyone have experience with this product or similar devices? Stock I was averaging 33mpg with my fit. Month ago, I added lightweight wheels, aftermarket intake and header now reaching 37mpg. I have a 07 Honda Fit Auto, Id love to hit 40 but kinda iffy bout these products.
Thank you.

Welcome to the site.

I'm not sure what an ETC throttle controller does for you. I'd imagine your foot can do the same thing though.

I'd recommend doing some simple aero mods to get the remaining few mpgs you're after. I grill block is #1 on the list.

I believe the device lowers the TPS signal to lean mixture. I have seen this before but don't remember much about it. Back when gas was four bucks a gallon.