And you thought the SL65 was the craziest SL of all time.

Ever since AMG was born in 1967, they have built some of the most incredible pieces of machinery you can lay your hands on. This week’s Car of the Week is an example of what they can do when they really try.

First released in 1999, this comfortable cruiser/supercar had a 7.3L V12 that was good for 525 hp. 0-60 was finished with in 4.7 seconds, and though it could easily be good for 200 mph,  it was limited to 155.

A Mercedes SL600

A Mercedes SL73 AMG

In true sleeper fashion, all that distinguished this from a regular SL600 were fatter tires, AMG rims, a double chrome tip exhaust and the badging. The interior had an AMG instrument cluster and steering wheel, but little else. A sleeper at its finest.

Despite all of this, it seems this Mercedes has disappeared from history. Only 85 SL73’s were produced, and there’s no word on how many of them are still on the road up to this day. Mercedes never even listed the SL73 on the price lists, and it was never sold in the US. But don’t worry, because its legacy lives on in a much less restrained car.

That’s right, the 7.3L engine that has been powering the Zonda for quite a few years now is nothing more than a tuned version of the SL73’s V12. The fact that the SL73’s powerplant is still a perfectly competent engine, currently powering one of the best supercars ever made, just cements the SL73’s reputation and its place as our Car of the Week.