While it may not be touting the old "Win on Sunday, sell on Monday" axiom we all know and love, Mazda recognizes that racing can only improve its cars. And so it's no surprise that the Japanese automaker is testing and refining its Skyactiv-D diesel engine by sending it out on various race tracks around the country – notably being the first diesel ever to compete at Daytona and the first to notch a Grand Am win at Road Atlanta.

Next up? Indy. It has been over 60 years since a diesel-powered machine ran at the Indianapolis Motor Speedway, and the Cummins-powered racer that competed in the 1952 Indy 500 with a 6.6-liter inline-six-cylinder oil-burner was a fast and brutal machine that set a new lap record in qualifying leading up to the race. Though that car was withdrawn with turbocharger failure 71 laps in, its diesel powerplant left an indelible impression on the racing community, and that's something Mazda hopes to accomplish once again.

Mazda says that the diesel engine in its race car is pretty darn close to stock – 51 percent stock by parts count, and 63 percent stock by weight – which means the way it performs in competition is at least a somewhat meaningful way to the stock engine's durability in the real world. Check out the image of the Mazda6 Skyactiv-D racer posing alongside the 1952 Cummins above (click to enlarge) and feel free to peruse the press release below for the rest of the details.
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MAZDA RETURNS DIESEL POWER TO THE BRICKYARD

July 25, 2013 (INDIANAPOLIS, Indiana) When the Mazda6 SKYACTIV-D Clean Diesel racecar hits the track at the Indianapolis Motor Speedway this week, it will be the first time in six decades that a diesel has competed at the most famous track in the world. Historians will note that the last time a diesel competed at the speedway was in the 1952 Indianapolis 500, when the Cummins Diesel Special surprised the establishment with technology unknown to most racers at the time. While there are no direct links between these two companies or their products, they share common goals in testing production technology in the harshest of environments.

While most people correctly associate racing with fast cars, it is far more complex than just raw speed. The best race cars have been optimized for efficiency in every conceivable area. Decreasing weight, friction, and aero drag are also key elements to performance. Less obvious to non-race fans is the fact that better fuel economy can mean the difference between winning and losing as fewer pit stops can often determine the winner in endurance races. Blend all of these ingredients together and you have the Mazda SKYACTIV recipe for racing.

Applying the same SKYACTIV methodology to both race cars and production cars, Mazda seeks the same ultimate goal – a satisfied customer. Racer customers want just one thing – a winning race car. Regular customers are far more demanding, wanting everything from superb driving dynamics, to great fuel mileage, and it must be wrapped in a good looking package at an affordable price.

The all-new SKYACTIV-D Clean Diesel engine in the all-new Mazda6 is a true production based engine. The engine is 51% stock by parts count, and 63% stock by weight. Mazda chose this path as it is the most honest way to demonstrate the quality, durability, and reliability of Mazda cars.

"This year has been one for the record books. In January, our SKYACTIV-D Clean Diesel Mazda6 became the first diesel racecar to ever compete at Daytona. In April, we became the first ever diesel to score a Grand-Am win at Road Atlanta. Now, we are about to bring clean diesel to one of the most famous proving grounds in the world, the Indianapolis Motor Speedway. Being students of motorsports heritage, it wasn't lost on us that the last diesel to compete at Indy, a Cummins, made a strong impact in the 1950's, hence our interest in looking at the state of the art from the past with our latest innovation," noted John Doonan, Motorsports Director, Mazda North American Operations.