BMW's
LMR prototype set the mold for every LMP to precede it. The single
roll hoop and raised footbox became the bench mark as soon as the LMR debuted
in 1999. BMW's modern Le Mans assault actually started off a bit
inauspiciously in 1998 with the V12 LM, but lessons learned contributed
to the very successful LMR. While the V12 LM was one of the first
car to incorporate a raised footbox and front nose diffuser it had an unorthodox
feature, the car took all its cooling air from the exhaust flow of the
front nose diffuser. This solution was less than ideal as front aero
balance was reliant on low ambient track surface temperatures. In
order to achieve ideal cooling, the car's front ride height would have
to be raised in high track temperature situations. 
In
'99 BMW completely redesigned the car starting with the cooling architecture,
revising it to take all the cooling air from the top surfaces of the car
in a more conventional manner instead of from underneath. The more
controversial feature of the car was the incorporation of a single roll
over hoop. But BMW simply utilized an over
looked rule within the ACO regulations concerning roll hoop design.
So, fixing the issues learned with the V12 LM and having a thorough read
of the rule book (and essentially designing two cars in two years!), BMW
set about the 1999 season to kick some ass! And ass they did kick.
