Aside from it being simply a G35 Coupe with AWD and some engine & suspension mods, we'll assume it has a different interior design as well.

Still, I'd be curious to see who can be convinced to pay nearly double the price of a G35 Coupe for those changes when the basic shell of the car still looks very much like a G35 Coupe. Oh it may be worth it from a technical perspective, but when you're talking $60-70k (assuming that pricing rumor holds true), it will take a lot of convincing for most buyers in that category to pay double the price and be driving around a car that still LOOKS very much like a G35 Coupe.

 

The production GT-R will look much different than a G35 Coupe, for better or worse. Manufacturers always disguise their test cars to keep the spy photographers at bay.