Over at F1 Fanatic, Keith Collantine has posted his F1 2009: Quick pre-season guide and this includes a list of the drivers and their numbers. In the comments a mini-discussion has developed because, as far as I am aware, the FIA have not assigned numbers to the two Brawn GP drivers as yet.
Nigel Mansell and Red 5
The present system for allotting numbers is dependent upon the finishing position of the teams in the previous season, apart from the Drivers Champion, who is always given number 1 and his team mate number 2. Thus Hamilton has number 1 this year, even though McLaren did not win the Constructors Championship. It is a convention that the lead driver in each team is given the lower of the two numbers allotted to the team, although this does not always hold true, as in the case of STR this year; Buemi, a rookie, is number 11 whereas Bourdais, surely the lead driver in view of his greater experience, is number 12.
Numbers tend to be of academic interest only these days anyway, partly because the system of assigning them according to the previous year's positions means that they change every year, and also because so many teams do not have an overt lead driver policy, rendering the allotment of lower and higher numbers less meaningful. It was not always so, however.
Until recently, the teams retained their allotted numbers year after year, only the champion and his team mate receiving 1 and 2, while the outgoing champion and team mate took the relinquished numbers of the winners. This meant that a team could keep their numbers for long periods and Tyrrell, for instance, retained numbers 3 and 4 for over twenty years. The result was that numbers often became associated with particular drivers, Gilles Villeneuve's 27 and Nigel Mansell's Red 5 quickly emerging as a sort of trademark that was instantly recognizable.
NASCAR has a system that allots numbers to drivers permanently and the fans frequently refer to their favorite drivers by number only, while the commentators almost exclusively refer to the cars by number. F1 escaped such a close association between driver and number, perhaps because there were usually four numbers that changed season to season.
Back in the eighties, the FIA mandated a reduction in the size and positioning of numbers on the cars. This was largely because the numbers were taking up valuable advertising space but the new specification resulted in the numbers becoming illegible to race viewers. This robbed the numbers of significance; it was only the rabid enthusiast who would memorize each driver's number. I would be quite surprised if a survey were to reveal that a majority of F1's TV audience even realize that the cars have numbers on them.
So the matter of driver numbers is an acquired taste at best. The real enthusiasts can delve into them in a quest for hidden significance (BMW has swapped Kubica's and Heidfeld's numbers this year - accident or a measure of the team's assessment of their drivers?) but the truth is that they have no meaning at all, beyond the champion's number 1, of course. They can be classed as one of the fine details of the sport, something that we discuss over the long days of the off season, when nothing else is happening.
But I notice that Sutil has a lower number than Fisichella...
Update
Keith's timing is perfect - today the FIA has issued an amended entry list which assigns the numbers 21 and 22 to Button and Barrichello. The Force India drivers move up to 19 and 20, Sutil still ahead of Fisichella and the Ferrari drivers swap numbers, Ferrari having requested this in view of Massa's greater points score last year. Toro Rosso too have asked for Bourdais to be listed first and he becomes number 11, Buemi moving down to 12.