Volkswagen own Porsche... and now that Hasbro/TakaraTomy were allowed to do MP Bumblebee as a VW Beetle, it should be possible now to do Jazz.
VW/Porsche weren't interested before the Movies started (for the Alternators & early MP lines), but dollars will always speak loudest, and the billions in global marketing that GM got with their partnership with Transformers Movies, would have any car company begging to cash in, and do anything in return, like allow for their cars to be done as toys.
Something that was probably the case for the Bumblebee Movie. Hasbro and Paramount wouldn't have done anything or paid anything to have access to the VW Beetle design (for the movie and for the toys). If VW had said no, it would have been another car model used, and the nod to the 80s fans just would have been absent (without too much complaint).