MPG?

[jonathan180iq]

Yes. But, over the long haul, it's not going to make a HUGE difference.

[Easy Rider]

Originally Posted by GZ250

I hear the fumes escapin the gas tank. This will obviously give a less milage. am i right?

Yes but probably not even enough to be perceptible (like maybe .001 mpg).
After all, some of what is escaping is AIR that is let in as the fuel goes down.