I really don't think the TPTCC situation is acceptable, nor do I think that
the PWF models needed to be changed much from their correct dimensions.
Overall lengths of the production cars that these models are based on:
Viper Competition Coupe: 184.1 in.
Corvette: 179.7 in.
Mustang: 183.2 in.
Ford GT: 182.8
Jaguar XK: 187.4
The Viper, Mustang, and GT are less than 2 inches different in length. To
fit the same box the Vette would have to be stretched, not the Mustang, but
you are correct that the Jag would have to be shrunk. Thing is, the claim
has been that the Mustang is short and that cannot be the case if they are
modelled correctly. If anything the Vette should have the worst problem as
it is the shortest and will be hitting everybody without ever appearing to
make contact.
The max difference we have is only 8 inches, which would be 4 inches front
and rear if the car is centered in its box. Taking the concept a little
further, why not set the collision box to the median size, ~184 in., and
allow the longer cars to stick outside the box slightly, making sure that
every car is centered in its box? Then you would literally be able to get
within 2 inches visually before a collision happens, and in some cases
(longest vs. shortest, avg. vs. avg) the appearance would be approximately
correct. I have never seen anyone online succeed in getting within 2 inches
of another car without bumping, even when the collision boxes are correct.
Even 6 or 8 inches would be pushing it online, particularly in road racing.