* GL350 BlueTEC: 3.0L V6 Turbocharged Diesel engine producing 240 hp and 455 lb-ft of torque
* GL550: 5.5L V8 Turbocharged engine producing 429 hp and 516 lb-ft of torque
There was also a GL63 AMG model available with a 5.5L V8 Biturbo engine producing 550 hp and 560 lb-ft of torque.
To determine the specific engine in a particular 2013 GL-Class, you'd need to check the vehicle's VIN or documentation.