I have a 2012 Honda Fit and I believe it has a 10.6 gal fuel tank. I was wondering if anyone ever swapped for a larger capacity fuel tank? If anyone knows or has a best guess, how easy/difficult is this and how big do you think I could go and is this even possible?

 

Well the fuel tank is placed in such a way to allow the rear "magic" seats to perform their tricks. I doubt there is room to add a larger tank and if you did you have now compromised the safety testing that was done.

Best thing would be to increase your MPG. Have you heard of hypermiling?

 

Yeah- if you can't stretch your tank, stretch what you can do with your tank. The Fit really rewards even minor hypermiling efforts.

 

The fuel tank is underneath the front seats on the Fit. It's not practical to swap it out for a larger tank—it's made to fit the space already.

If you really need a larger tank, the best option probably would be to install a (good quality) fuel cell in the hatch area. I don't know what all would be involved in doing that safely and legally, but I suspect it would not be a simple process, and you'd lose a lot of cargo carrying capacity.