Why Did The Cars Numbers Change?

Exactly.

 

For years and years and years. Take some time and read up on Grand Prix racing, makes the sport much more fun.

 

They changed it in the mid 90's.

 

This article is from the Motorsport FAQ, by A H Henry [email protected] with numerous contributions by others.

How are F1 race numbers allocated ?

Before 1973, F1 drivers raced with different numbers at each race.
Teams in the world championship had to submit their entries to each
individual race organisation and were then given their race numbers by
the organiser. Number 1 ( # 1) was used by either the defending
champion of that race, the world champion, the first team to submit
their race application, or the favourite of the organisers.
By mid-1973, FOCA (the Formula One Contructors Association) united
the teams who now entered the races with one joint application. FOCA
now took over the assignment of race numbers. At first, each team was
given a random number, which it kept until the end of the year. The
numbers were given to the team, but not drivers, so Stewart drove as
both # 5 and # 6 in the latter half of 1973.
In 1974, the modern system took hold. At the start of the 1974
season, the teams were given the numbers according to the final
positions in the 1973 Constructors Championship. Hence Lotus got 1 & 2,
Tyrrell got 3 & 4, McLaren 5 & 6, Brabham 7 & 8 etc. If a team had more
than two cars, the extra car was given a high number like 33.
These numbers are only changed when a new driver wins the the
Driver's World Championship. In this case, champion and his teammate
are given 1 & 2, while the previous champion gets the old number of the
new champion. If a driver changes teams after winning the Championship,
he takes the # 1 to his new team.
For example in 1977, Ferrari ( # 11 & 12) won, but Lauda moved to
Brabham. So in 1978, Brabham raced as 1 & 2, McLaren (champions in
1976, who held # 1 & 2 in 1977) got 7 & 8 (Brabham's 1977 numbers),
while Ferrari kept the 11 & 12. Tyrrell have kept numbers 3 & 4 for 20
years because they had not won the championship since 1973.
Before Nigel's Mansell's retirement, some non-champions did drive as
# 1. Ronnie Peterson got the # 1 in 1974 because this was the first
year. In 1985, Watson drove # 1 because he was Lauda's replacement.
However, after Mansell's retirement and possible unretirement, which
made the numbering system unclear, # 1 was declared being 'personal'
and only for the world champion, so Damon Hill got # 0 for 1993 in the
Williams.
The numbers have been personalised for the past few years. Hence when
FIA gave out a number, it is both for the team and the specific driver.
Nowadays the numbers are given alphabetically, with the driver whose
last name is first in the alphabet receives the lowest number. Of
course, you can always request a change.
Occasionally, if a team expires, a team with a high number will move
to occupy the old team's numbers. When Renault left F1, March took over
the 15 & 16 slot. Same rule applies to Brabham, but in this case it was
unusual involving a three teams switch: Larrouse > Benetton > McLaren >
Brabham. This had never happened before.
Careful study of the race numbers shows some of the relationships
between the teams. Take 19, 20 & 21. These were the old Williams
numbers in the 70s. When Walter Wolf took over, Team Wolf got # 20,
while Williams, who re-started his new race team, got a new number of #
27. By 1980 when Wolf had merged with Fittipaldi, Fittipaldi got rid of
its old # s and got 20 & 21.
Some numbers have special significance for some of the fans and
drivers. Thirteen is considered to be an unlucky number and is missing
from the F1 lineup. Gilles Villeneuve raced as # 27 during his finest
years which makes it a special number for Ferrari fans. Nigel Mansell
drove as Red Five for Williams, although this number has since been
taken over by Michael Schumacher's Benetton.