When this Mercedes W123 rolled out of the factory it was powered by a 2.8 L M110 inline-six engine but recently this crafty owner decided to increase the cylinder count and displacement of the engine in his wagon by more than double. So the owner found a rare 7.3 L AMG M120 V12 and automatic transmission sourced from a Mercedes S73 W140. The engine produces 558 horsepower and over 720 Nm (531 lb-ft) of torque. These are the same engines Pagani used in several Zonda models. You can see the engine is taking up every inch the engine bay has.