You are asking the world's biggest collection of "look-at-me" types why they would want the same for their offspring?
Seriously, though, I think there is one important point to consider beyond what has been discussed above. That point goes beyond the maturity of your child, his resistance to peer pressure, and his driving skills. This other factor has to do with the environment of teeenagers' social situations and how they differ from those of adults.
How many posts have you seen on this forum where somebody tried to box a Viper in on the freeway, followed on his bumper trying to get him to race, or slammed on the brakes in front of him? How many posts about cars getting keyed, sat on, poured crap in, or worse? Gee, ever been pulled over in your Viper for no apparent reason (no? well, you're the only one!).
So what do you think it will be like for your son at the A&W? Adults respectfully admiring your car like when you are at the dealership? Try punks looking to "one up" your son, push him around, try to pressure him into a race, maybe damage your car out of spite or envy. How about other kids getting their testosterone going, doing burnouts, racing, etc to prove their still men with your Viper sitting there getting all the attention. What about all the attention the local law will be giving him? Hard enough to avoid a ticket as a businessman in a suit, what about when you're 17?
The risks of driving are not just internal, most are external and beyond your control. Driving a Viper is pouring gasoline on those flames each and every day, for us and more so for your kids.