FH1100:
Nice to see you again!
There probably isn't enough distance to travel to make a difference in the soda. The fuel tank is at least 4 to 5 feet wide and has a lot more mass. Also, if your soda was distributed in a long tube across the cockpit, you'd see the difference.
At least that's what I'm coming up with right now.
And Longbox - I'd love to know what they've changed since I flew it in 2003.