A main difference between the new Dodge Challenger GT and the R/T is their engines. The Challenger GT utilizes a 3.6-liter Pentastar V-6 engine with 303 horsepower, while the Challenger R/T is equipped with a legendary 5.7-liter HEMI V-8 engine, generating up to 375 horsepower. An Electronically Controlled Active Exhaust system is also standard on the Challenger R/T.