This guy were looking for business partner at Actoys.net for using these design to produce some unauthorized products before official licensed. But…this user left a mystic avatar.
The last thread this guy left in Actoys.net, is about sell die-cast Chevy Corvette ZR1 model. Looks like this guy is a die-cast car model seller and he claimed this is ZR1’s head.
Until recently the alt mode of "Stinger" was known to be a Corvette, just not sure which one. I and others thought it was the ZR1. It has since been pretty much verified to be a Corvette Centennial. If the person was on the TF2 design team, then they would have known exactly what model car was being. Since clearly they didn't, safe to say this is a fan-made design. Nicely done one though.
S250 on TFW2005 forums has now provided the full body image of the Transformer. Overall a pretty good looking design but I sticking with my fan made theory.