I would say it is in for sure as they seem to have all the cars from GT4 and it was there in GT4. It will likely show up in the used car dealer at some point. Hopefully you will have enough levels to buy it when it appears.
I found the Fireblade last night and tryed to buy it but I was only at level 7 and need to be level 14
No S7TT or S5S Raptor unfortunately. Would have been a good homage since Saleen supercars are basically no more. Hopefully you can still turbocharge/supercharge the S7 like in GT4.