Uh, I'm pretty sure you got Stone buddy. You can't get IP/Wheat on a Sport model G Sedan. For '07, IP G Sedan Sports were only available with Stone (Gray) or Graphite (Black) interior. The Graphite interior has since been discontinued leaving Stone as the sole interior option on Sport model IP G Sedans so no, your interior is not rare at all. What color is your dash? If it's black you have Stone interior and not Wheat. Wheat (Tan) interiors have a brown dash and center console. I think you're confusing Stone with Wheat.

*Edit*

Just found this thread. https://g35driver.com/forums/picture-share/128578-pictures-my-2007-ip-sportsedan.html

You have Stone interior my friend, not Wheat.