To understand why Mercedes-Benz calls the 2007 S65 AMG the “world’s quickest four-door,” you need to know just two figures: 604 horsepower and 738 lb.-ft. of torque. The sad thing is, most S65 AMG buyers will want it because it’s the most expensive S-Class in the stable, and not because they actually plan to drive the thing.

That means the engineering expertise that goes into the motor is lost on most S65 AMG owners. Stuff like a precision-balanced crankshaft with a longer stroke, larger-bore forged pistons, and upgraded oil-spray cooling and bearing lubrication systems. But we’ll bet that if friends and family want to pop the hood, they’ll be impressed that the single AMG engineer who built it, from start to finish, also hand signed it.

Expect to pay a pretty penny when the 2007 Mercedes-Benz S65 AMG goes on sale later this year, but when it comes to high-end Benzes, price is a moot point.