Because we are so clever (humans) and we have made giant leaps in the last couple of years (10) there isnt really much more physically that we can do to make a car faster as far as the chassis layouts are concerned. All we can really do with our current technology is make it stronger and easy to work on, more adjusable maybe. but at the end of the day all cars that are top end. Tamiya TRf 415s, Xrays, Pro 4s are never all going to be "Dialed" in to its fullest potention on any one track. for instance i bet at the snowbirds all of the cars in the A-final could of had a small adjustment that would have made them faster....
we should be concentrating on finding the optimum setup for the cars we have than designing new cars that LOOK FAST.