I have sat in the older vipers and the newer ones and I have one word to sum them up: small. The newer ones are a little better but the older ones are almost impossible to get into. You have to crawl into them, and once your in, there is hardly any room. Now I'm 6'4' but still. Another problem is the side exhaust. One of the older ones I sat in had side exhaust and you could actually get burnt getting out of the car due to the exhaust.

 

Same with the new ones