I was drooling over the photos of Toyota's GTP on MulsanneMike's website this morning when it struck me that the ACO 2004 rules would seem to produce a rear diffuser strikingly similar to the very effective diffuser employed on the all-conquering MkIII.
From the 2004 ACO rules on Mike's website:
3.5.2 - Rear diffuser
An inclined surface (rear diffuser), flat, continuous and rigid is mandatory underneath the car and at the rear.
a/ It must be inclined relative to the reference surface and it must comply with the maximum volume defined by
drawing n°1 ;
b/ No part of the diffuser must be more than 200 mm above the reference surface and its rear end must be plumb
with the perimeter of the bodywork ;
c/ The panels joining the rear diffuser to the reference surface must be vertical. In addition, from the rear axle
centreline to the rearmost edge of the diffuser, the outer panels joining the rear diffuser to the reference surface
must remain parallel to the longitudinal centreline of the car ;
d/ A maximum radius of 10 mm is authorised to connect the rear diffuser to the vertical panels ;
e/ A maximum of two vertical fins may be added to the rear diffuser, but their surfaces must :
e.1 – be at right angles to the diffuser ;
e.2 – be flat and parallel to one another and to the longitudinal centreline of the car ;
e.3 – be positioned symmetrically about the longitudinal centreline of the car.
Now, having read that, check out this photo of the rear diffuser on the Toyota...
http://www.mulsannescorner.com/toymkiii-5.html
Notice that there is a full width flat reference plane ahead of the diffuser, then the diffuser rises to what appears to be no more than 200 mm. And there is one rules-compliant fin per side.
The Toyota was an exceptionally grippy car. Perhaps I underestimated the down force potential of the new rules...
