Well, we can all assume the RB chassis to be pretty well sorted, so by implication, not much room for improvement. However these are inherit advantages that RB has in it's favor ..
A healthy points lead DESPITE the fact that the races still haven't been problem free.
Probably the best understanding of the tires of any team so far, especially via Webber, who has had to race hard and learn the tires well to get his points.
KERS just coming on line.
As the leader in car design they know what problems they have that others have gotten to yet, whether it's aero balance, starts, etc. We can assume they are working diligently on whatever items they can find improvement in.