I didn't mean he was actually driving it faster than it was capable of, as you say, that doesn't make sense and isn't actually possible. I meant that in that car he shouldn't have been so close to winning the title but he was because he took pretty much every opportunity that came his way and made hardly any mistakes whilst driving on the limit. The Ferrari was, at best, the 3rd quickest car over the course of the whole season and as such he shouldn't of been so close to the WDC. That was the "potential" of the car, Alonso outperformed it by a fair bit.
Not quite. Lets just put this 'Alonso was flawless all season' bs aside and take a closer look.
1) the fastest car, Mclaren, took itself out of the equation with its own many faults, leaving #2 (RBR) and #3 (Ferrari) to fight it out for the title.
2) both Fernando and Sebastian got involved in two major incidents over the season, one of them being a racing incident (Rai/Sen) and the other resulting in the causing driver getting a penalty (Gro/Kar). Fernando's 2 incidents roughly cost him 20-25 points (3rd/4th in Belgium and 4th/5th in Suzuka ), while Seb's incidents cost him 15-20 points (3rd/4th in Malaysia and 3rd/4th in Brazil). (net gain of about 5 points for Seb)
3) but Sebastian, inspite of having the faster car, also lost a rough estimate of about 35 points (42 to points to Alonso when you consider that Alonso gained 7 extra points due to his retirement in Valencia)due to his 2 car failures. (net gain of about 42 points for Fernando)
4) both Seb and Fernando were outperformed by their team mates for 3 races each this season. But while, Mark was allowed to take points away from Seb on all 3 occassions, Felipe wasnt allowed to on even one instance. If you take one position away from Fernando in those 3 races it comes to 9 points, but I shall halve it and make it 5 points. (net gain for Fernando 5 points)
Net gain for Fernando = 47 points
Net gain for Seb = 5 points
Final result = A net gain of 42 points for Fernando
So you might say Fernando had a much slower car and he came to within 3 points of Seb. But one must ask the question of why? And the answer lies in the reliability of the RBR, for if not for its failings, Sebastian might have come close to sealing the title with two races left.