Utility
The SL-Class is a better choice than the Dodge Viper as far as hauling capacity, especially if you frequently need to carry a lot of loot or massive animals.
Neither the Viper nor the Mercedes-Benz SL-Class has a marked advantage when it comes to seating capacity.
Dimensions
The Mercedes-Benz SL-Class is quite a bit more ponderous than the Dodge Viper.
The Dodge Viper and the Mercedes-Benz compete for the same parking spaces.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. The Mercedes-Benz SL-Class is markedly cheaper to get to the dealership than the Dodge Viper.
The Dodge Viper is tremendously less expensive than the SL-Class in terms of MSRP.
Handling
The Dodge Viper has substantially bigger tires than the Mercedes-Benz SL-Class. Remember that bigger tires can look and feel better, while narrower tires could improve gas mileage.
With its tighter turning radius, the Mercedes-Benz SL-Class is quite certainly sprier than the Dodge Viper, something to consider if you do a lot of city driving; however, keep in mind that a vehicle with a tight turning circle may feel a bit twitchy on the highway.
Drivetrain
The Mercedes-Benz's engine is substantially smaller than the Dodge Viper's. Keep in mind that smaller engines can be stressed more; however, smaller engines are often cheaper to fix.
Comfort
Taller drivers will substantially enjoy the extra head room in the Mercedes-Benz SL-Class's front cabin compared to the Dodge Viper.
Overview
The basic warranty that comes with the Dodge Viper isn't quite as generous as the Mercedes-Benz SL-Class's.
In terms of after-sale protection against rust, the Dodge Viper has tremendously better coverage than the Mercedes-Benz SL-Class.
Other
The Mercedes-Benz SL-Class emits fewer smog-forming pollutants per 15,000 miles than the Dodge Viper.