Victory margins, was something i did think about looking into, but it dawned on me that its rather pointless, as clear leaders don’t drive their cars hard for the whole race, but tend to manage the gap and look after their car. So it rarely tells us the true possible performance.
Qualifying results and times against the opposition is also is not a good indication for these years, as the qualifying rules were changing from year to year. In 2004 they had to qualify with race fuel onboard. I remember Schumacher would often sacrifice grid positions, in favour of carrying more fuel to run longer in the 1st stint.
I also understand what your saying Ned about not comparing the out right speed of cars from different years. And their is clear arguments for either side of the F2002 v F2004 debate.
I think the “what was the best car in the 2000′s that wasn’t a Ferrari?” question is an interesting one.
I think i would have to go for the 2006 Renault R26.