After the race ended I also started to think the new F60(B) must be quite heavy.
And/or with a small fuel tank.
Did you notice how evenly the stops were distributed? There's a chance they just couldn't get more fuel in there, and all this talk about malfunctioning machinery is just a smokescreen.
I would suggest that the new diffuser is heavy, that they didn't have the time to redesign the car around it properly, and so had to cut something. The only simple and obvious choice is the fuel tank.
They _could not_ have guessed when Vettel was coming in as Massa was always ahead, so the choice of running the hard tyre compound for so long must have been forced onto them by some solid reasoning. Small fuel tank fits there.
Also, did you notice how Kimis KERS at one point seemed to be completely spent - and the suddenly was fully charged again without any breaking? Kimi then used just a fraction of this newly acquired charge.
What was it? A second KERS battery? (bold treatment of rules in encouraged now, you know
) Or am I seeing things?