Funny graph))) Reminds me of that marketing tricks to lure client into believing their product is sooooo much better. Draw full bars (from zero) and you'd see a really tiny difference.
The only thing that can be deduced from this graph is - aero (or engine maps?) rules.
I've used graphs just like this myself. Very sneaky indeed, but the data does bring up an interesting notion. If the full race fuel regulation applied to last years cars would result in something like a 6kg difference at the start between the Merc and the Brawn with full race fuel, imagine what you could do if you designed the aero with increased attention to drag reduction at the expense of downforce for 2010. If teams could reduce drag to the point where they start the race 25kg lighter than their competitors, that is a big difference, and they would be faster at the start and difficult to overtake until the fuel weights were equalized towards the end of the race.
I think the 2010 regs move the sweet spot between reducing drag and maximizing downforce more to the side of reducing downforce. At the very least, teams will have to make a choice about where the new sweet spot is.
It could also lead to some interesting races, with the teams who favored drag reduction strong at the start of races and the teams who favored downforce stronger at the end of races.
Maybe I'm just being optimistic, but tying fuel efficiency to potentially significant weight savings does move the goalposts.
Just a thought.