The financial calculation will never hold. If you buy it and rarely drive it, then you must have a "******" to drive instead. The appreciation of the Viper then has to overcome the small amount of miles you put on it plus the cost of ownership of the ******. In the meantime, you've substituted miles in the ****** for miles in the Viper... ummm.... say again why you force yourself to drive the second-best (or third or fifth-best) car you own?
What do you think a $25,000 Viper will be worth in 20 years? $250,000? If so, that's a 12% annual appreciation. A $50,000 car going to $500,000? Same thing. A $50,000 car going to $1,000,000? You've earned 16% per year.
Those $500,000 Cobras were $10,000 in 1965. 10% per year.
Someone will say that's still better than a $50,000 car being "only" worth $50,000 (or less) in 20 years, which is obviously true. But then you've paid $0.50 mile to drive that ******, which is $7500/yr. A $7500/yr investment for 20 years at 12% has a future value of $540K, which is now a lost opportunity.
Rather than have fun with the numbers, have fun with the car.