If pcars isn't a sim then neither are the Simbin titles I have enjoyed so much over the years. in the end, that argument is largely subjective.
Only your opinion, but the opinion I hold is that these are sims....
Iracing
rf2
Simbin GTR-2011
GSC 2011/12
Netkar pro
All these games share a similar feel, with some games and some cars from each of the games being better than others, so for example, even though GSC's Camaro is probably the best tin top sim car{IMO}, the same model in RACEON isn't arcade, it just isn't as good as it lacks the detail of FFB and overall car behaviour, but even the ordinary SS Camaro from RACEON has a very good mix of FFB, steering precision and physics.
If we look at pcars, the 2 most striking problems for me are the center sprung feel and the weaker less detailed FFB, and under no circumstance will I ever rate a center sprung driving model as a sim, simply because you sacrifice so much feel and car behaviour.
As depicted beautifully by Adrian's diagrams, the best sims or even the typical sim has more of a 4 point contact feel, and this is demonstrated by many sim cars from the list above, with rf2's F2 probably being the best example, though it's form factor helps, but nevertheless, it's a great example, as is the GSC Camaro, GTR EVO C6R, RACEON US Muscle Camaro etc, etc.
This to me this is the challenge SMS face, can they remove or tweak that feel out of the PC spec, I certainly hope so, but I'll be buying this game regardless, but please, it's quite ridiculous to call it a sim when it has a such a digital underpinning.
I should also point out as I've done before, it doesn't matter to me which is the best sim car, only that it is a sim car, so I don't care one bit if someone thinks iracing's C6R is better than Simbin's, I only care that they have such a combo of steering precision, FFB and physics which translates into a high degree of realism and thus being worthy of the term simulation.
For those reading this thinking that pcars is absolute crap, well that's not true, it's certainly worth the buy in price of junior IMO, and it has heaps of potential as a game, but it remains to be seen if it even becomes a sim let alone pretending it's currently comparable to the established sims.