putting in extra screws up the gas level reading I think.
and it ruins your carbon cartridge

 

my stick goes to below F between 34-40 miles! and about 140 at half tank! light comes on at about 260! i only get about 29mpg of highway driving and 20 if local driving..

 

Several ppl have said this to me previously. I have yet to have someone tell me WHY!

I've been doing this, topping off the tank, on my cars for many, many years with no obvious problems.

Can someone tell me SPECIFICALLY what the harm is in topping off the tank?

Yes, I top off my tank, and always put more in than 10.8 gallons.

 

I think the issue is that the evaporative emissions return tube which returns gas vapors not used by the engine to the tank connects high in the filler neck. If you fill it up past that opening, it can flood the emiisions components with liquid gas, instead of the vapors they are designed to deal with.

 

WOW! I have never been able to fit more than 9.8 gallons in my fit, and that was after driving it 35 miles with the fuel light on.

Another WOW on the 398 miles. I got 358 once, but that was pushing it.