The underside of a Gran Turismo 5 racer reveals this curiosity: the logo for die-cast collectible maker AutoArt (lower side, centre).
No one's suggesting they base the entire car on AutoArt die-casts, but it looks like at least a generic undercarriage from one was used here.
Update: Looks like this is an Easter Egg. Reader ShiryuGN supplies this picture of an actual AutoArt undercarriage; it has no logo, like the one above.
Thanks wh33z3r for the tip.