Seven-oh-seven horsepower. In a full-size American sedan. Let that sink in. The 2015 Dodge Charger SRT Hellcat is the most powerful production sedan ever built. And with a claimed 204-mph top speed, Chrysler says it's also the fastest production sedan ever. The fact that the Charger has four doors makes it even more ludicrous than its two-door Challenger counterpart, which we loved dearly in our First Test and a comparison against the supercharged 580-hp Chevrolet Camaro ZL1. (The supercharged 6