I have an 06 Civic Coupe and when I fill it up, if let's saythe pump stopped at10.1 gallons then I will add another gallon, slowly making it 11.1 gallons. I am wondering about the EVAP system if that could be getting contaminated with fuel.
By doing this I have gone 325 miles and still showing 1/2 tank of gas.

Any ideas if this is going to hurt the car?

 

This is what peeople say...

When filling up the tank never "top it off". Newer vehicles have electronic gauges which work by a piece of metal attached to the float arm that slides across metal contacts (called a sending unit), to indicate how much fuel is in the tank. "Topping off" can push this contact beyond its limits and damage the sending unit leading to inaccurate readings of the fuel gauge.

 

A couple of people here have reported getting their gauge stuck on full. Also if you spill some gas on the ground in the process of topping off, it kind of defeats having an EVAP system in the first place.

 

ya im preaty sure that my chevy truck 93... got messed up when refueling it... needle on the gauge went to about 1 and 1/2 full.LOL
but i did that with a farm style gas pump.. high flow pump and i was pumping it preaty quickly to just get done... and well so far like 200miles on the tank and it still says 3/4 a tank. i typicaly set the pump on the next to last catch so its not full speed pumping unless gas pump is VERY SLOW... and only go about 5 click off attempts to top off...
BUT if your looking for gas milage dont fill up... less fuel =less weight from fuel... BUT to me i just fill up myself..