This race isn't about which sport sedan crosses the finish line first; it's about which one hits 186 MPH the quickest.

Assuming you have the money to spend on a midsize performance sedan, then this is a great time to be in the market for one. Options like the BMW M5, Cadillac CTS-V, Mercedes-AMG E63 S, and Porsche Panamera Turbo S E-Hybrid are all performance powerhouses that blend luxurious interior spaces and easy high-speed driving. Thanks to Germany's Sport Auto, we now know which one of these four-door muscle machines hits 186 miles per hour (300 kilometers per hour) in the shortest amount of time. 

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All the members of this quartet use a V8 engine with some form of forced induction. The M5 arrives with a 4.4-liter biturbo V8 producing 600 horsepower (447 kilowatts) – although a dyno test suggests BMW underrates this figure. The CTS-V uses a supercharged 6.2-liter V8 producing 640 hp (477 kW). The E63 S packs a biturbo 4.0-liter V8 with 603 hp (450 kW), and the Panamera Turbo S E-Hybrid features a biturbo 4.0-liter V8 with extra hybrid assistance for a total system output of 680 hp (507 kW).

Racing to 186 mph is an arbitrary test for most countries, since reaching those speeds on public roads would equate an immediate trip behind bars if local law enforcement catches you. However, Sport Auto is in Germany, and the unrestricted portions of the Autobahn at least make these high velocities conceivable for ordinary motorists.

While we don't want to spoil the winner of the race, the Cadillac is the definite loser of this trial. While the other three are able to reach 186 mph, the CTS-V seems to run out of road before hitting that speed. It hits 178 mph (287 kph), and the driver then starts slowing down.

Source: Sport Auto via YouTube