Two ways:
1. The mainline Viper was leaked several weeks ago and featured on several sites, most notably by our good friend Doug over at T-Hunted. The pic he featured:
Now compare that to the Viper I featured yesterday, given away at the NY Auto Show:
The color appears to be the same, as are the wheels. But note the stripes and hood detailing on the leaked photo, as well as the lack of an SRT badge on the side. It is also hard to tell, but the NY model has the hood intakes printed black, and rear detailing. The leaked photo does not show it, but there is no detailing on the rear.
Well, you might wonder if the leaked photo is of a model that was later scrapped. That is where reason #2 comes in.
2. Posted on a thread about the Viper on HWC by HW designer Steve Vandervate:
"The version shown in the link is not the same as the Basic retail version. A small number were produced for the show and had no stripes, but additional deco (hood vents, rear fascia) to replicate the car as it debuted at the show."
So the model handed out at the show is unique. For me a model easily worth picking up...