1991-1993 Toyota Eagle MkIII

Images copyright Michael J. Fuller and Ryan Hicks
Text copyright Michael J. Fuller

The Eagle MkIII wasn't necessarily the first sports cars to utilize a front underbody aero concept designed to develop downforce.   Even the very first GTP cars were looking to take advantage of that area to generate localized low pressure to improve front balance.  But this became a goal very early on in the initial design studies for the MkIII, to exploit this area to maximum advantage:

1. Develop a very narrow tub to maximize air passage between the front wheels
2. Build a front ground effect section in front of the front wheels similar to a standard front wing in plan view
3. Provide a large escape area behind the front wheels and out the side for the air to be exhausted from under the front ground effect section
4. Work to minimize deleterious effects of the front tires on this exhaust area...

And the AAR design team executed exactly along those lines.  The MkIII was most definitely the first to take the front underfloor aero concept to the next step by intentionally exiting the airflow from the front diffuser out the side of the car and fully providing for as clear a path as possible, both into and exiting the diffuser, for the airflow.
Toyota Eagle MkIII IMSA GTPThe diffuser forms extensions either side of the slightly raised tub.  The spinning action of the front wheel further draws airflow through the diffuser.
Here we can see the extensions of the diffuser upsweep and their proximity to the front wheel and suspension members.  Leading edge sculpting just behind the wheel encourages air to leave via that path.
In this shot the front splitter has been removed (hence the daylight in the top portion of the image).  Here you just begin to get an idea of the clear path the airflow has out the car via the outlet aft of the front wheel.

ęCopyright 2008, Michael J. Fuller