Regarding the diffuser:
2008 regs wrote:
3.12.1 All sprung parts of the car situated more than 330mm behind the front wheel centre line and more than
330mm forward of the rear wheel centre line, and which are visible from underneath, must form surfaces
which lie on one of two parallel planes, the reference plane or the step plane.(...)
3.12.2 Additionally, the surface formed by all parts lying on the reference plane must :
- extend from a point lying 330mm behind the front wheel centre line to the centre line of the rear
wheels;(...)
3.12.7 No bodywork more than 150mm from the car centre line, which is visible from beneath the car and which
lies between the rear wheel centre line and a point 330mm forward of it may be more than 125mm above
the reference plane.(...)
3.12.8 All sprung parts of the car situated behind a point lying 330mm forward of the rear wheel centre line, which
are visible from underneath and are more than 250mm from the centre line of the car, must be at least
50mm above the reference plane.
In short, a current car must have its diffuser placed between the rear wheel center line and a line 330mm forward of it, with the reference plane/plank extending to the rear wheel center line. Max height is 125mm (out of the central section) and only the central section is allowed to be lower than 50mm.
In comparison with 2008 regs, 2009 ones force the diffuser to be moved rearwards by 330mm, whilst allowing it to be a bit larger:
2009 regs wrote:
3.12.1 All sprung parts of the car situated from 330mm behind the front wheel centre line to the rear wheel centre line, and which are visible from underneath, must form surfaces which lie on one of two parallel planes, the reference plane or the step plane.(...)
3.12.2 Additionally, the surface formed by all parts lying on the reference plane must :
- extend from a point lying 330mm behind the front wheel centre line to the centre line of the rear wheels;(...)
3.12.7 No bodywork which is visible from beneath the car and which lies between the rear wheel centre line and a point 350mm rearward of it may be more than 175mm above the reference plane.(...)
3.12.8 All sprung parts of the car situated behind the rear wheel centre line, which are visible from underneath and are more than 250mm from the centre line of the car, must be at least 50mm above the reference plane.
D'leh, I considered 3.11.1 only to move the front wing forwards in my side view sketch, that was all.
Keep your ideas coming, they're enlightening.