Looking to source a 35 gallon tank to do the swap on my 2015 I found this...

Seems to indicate the tank is the same, and they have some sort of limiting device in the tank preventing you from fully filling it up?

http://www.cleanmpg.com/forums/showthread.php?t=51614

 

I'm just glad I don't spend 2 hours topping off my tank....

 

Pretty crazy experiment. From the schematics posted, it does look like there are 2 different tanks. My guess is that both tanks can hold more, and there must be a reason that the fill level is set where it is.

That guy needs to spend another 2 hours filling up the extended range tank to see.

Would be nice if there is an easy way to increase the capacity of either. A 1,000 mile range would be really something.

 

They have to allow for expansion of the fuel, that's why there is extra space in the tank.

 

And continual force feeding of "extra" gasoline can actually back feed into the charcoal canister. Complete liquid saturation in the vapor canistor can lead to catastrophic damage

 

4 options I see:

1 - two hours in the wind with the funnel stuck in to hold open the valve = 10 gallons of gasoline evaporated into the air.

2 - he filled all the air space with gasoline. Don't let it warm up or you'll have a mess!

3 - the charcoal canister is full of 10 gallons of gas, like Patman mentioned.

4 - the pump just shut off early (we've all seen it) and he was 10 gallons short at the beginning...

 

Did this one with my sports car. Overfilled tank by 5 gallons. I ended up getting 500 miles out of my Z on one full tank. You could damage evap controller or other items such as fuel level indicator.