again, the speeds dictate the need. a 968 won't exceed 120 on just about any track, and will never see the speeds that vette will.
it also does not mean that correcting the underbody issues would not have much the same effect, without the cost of drag. the 968 is very unfinished in aerodynamic terms. run a smoke stream under there, and you'll find out just how bad it is. i did. i designed the stuff to correct it, but never installed it, because i was never going to be going fast enough to need it, and once i got rid of the gas shocks and struts, and went to hydraulic, and added the larger swaybars, the need to increase downforce diminished, because the car was more settled, and didn't expose itself so much to underbody air. the belly pans and rear diffuser were also going to be a pain to deal with in terms of getting under the car and cleaning things. again, the need dictated by the speed.
aerodynamic resistance, or drag, increases exponentially with speed. a car that needs little to nothing at 100mph, will need a lot more at 140. a car that goes 210 is going to need a lot. a car that struggles to hit 150, not so much. unfortunately, once you increase the drag to produce the downforce, you also increase the need for power to overcome the drag. it's a never-ending battle against physics. it is extremely common to see things like every 30lbs of downforce meaning a need for an increase in power of 30hp, just to reach the same speed at the same rate. yes, you will stick better in a high speed corner, but you will watch guys passing you at lower speeds, that you never had issues with before, and you won't reach speeds you used to reach as easily as before. there is no free lunch here.
none of this matters much though. most tuners don't understand the engineering and physics, so they bolt on wings. it's simpler, faster and cheaper. no real testing is involved. no math is involved. it's easy to demonstrate the effect. these are all great sales tools. it still doesn't mean that the same driver, in the same car, wouldn't have benefitted more by other routes. that won't change until the customer is willing to pay for that education in their tuner. the unfortunate reality is that most drivers will never be able to take advantage of the difference either.
i'm not saying wings don't work. i'm saying that, at the speeds of the 968, there are better ways to get there.
back on topic - the jag was a 2007 s type i think. the episode was in 2011. clearly the 968 should spank the s type, but i thought it was particularly funny to see the reverse.
maybe a new jag F ( the R version ) has a chance on the track against a 968, or, the XJ 220 , lol, but not many other jags.. 