The bladder capacity definitely depends on temperature.
In the colorado winters, most fillups are around 8-9 gallons
In the summer, it's ~10 gallons. 11.0 is the most I've ever put in.

Also, it may help to fill at a slower rate (but don't top off - bad for the air and for the car).

2004 Tideland, Package #7 (all safety options) + EV
70000 miles at 49.0 mpg avg.
Louisville, Colorado