It's hard to say which car is the coolest in the world, but Steve McQueen's 1956 Jaguar XKSS certainly makes our shortlist.

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This singular Jag currently resides in Los Angeles' Petersen Automotive Museum, but Jay Leno got to take it for a spin on the latest episode of Jay Leno's Garage.

It goes without saying that Jay has access to come fairly amazing machines, but the XKSS stands out. The model was essentially a road-going version of the D-Type racer, and only 16 were built. McQueen and a subsequent owner drove this one around Los Angeles for years, and now it's reportedly worth over $25 million.

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Yet even without all of that provenance, the XKSS is still a great car. The styling rivals anything on four wheels, including Jaguar's own vaunted E-Type. The inline-six makes an unbelievable sound as it breathes through the side pipes.

Watch the full video for plenty of that mechanical music, and for more on what makes the XKSS one of the greatest (and coolest) cars ever made.