Mazda brings diesel back to Indy with 6 Skyactiv-D

Diesel has enjoyed great success lately as a racing fuel, but there's one place it hasn't appeared for more than six decades: Indianapolis Motor Speedway. Mazda's breaking that dry spell this weekend, when its Mazda 6 Skyactiv-D race car will head to Indy for the Grand-Am race.

We like the 6 in both road trim and racing livery, but that previous diesel-powered racer -- the Cummins Diesel Special -- is pretty neat too.

There were actually two Cummins Diesel Specials, a 1950 and a 1952, but the second incarnation saw the most success. Powered by a 6.6-liter turbodiesel cradled by a low-slung, streamlined Kurtis-Kraft body, the '52 Diesel Special must have shocked gasoline-powered racing teams when it appeared at the Indy 500.

Preliminary results were impressive -- the car even managed to break the Indy 500 lap record early in the race with an average speed of 139.104 mph. Unfortunately, it retired after a turbocharger failure on lap 70 and never raced again.

Comparing the two cars is a great PR move, we guess, but it's an even better excuse to pull out the Cummins for a photo shoot.

Mazda says its diesel 6 is the first oil-burner to race at Indy since '52, and while the Mazda racecar isn't in the same class as the Cummins Diesel Special -- and it isn't even competing in the same race as the earlier car -- it's a worthy vehicle in its own right.

The racing Skyactiv-D-equipped Mazda 6 has a 2.2-liter turbodiesel inline-four, but its tune is a wee bit more aggressive than that of the 2.2-liter diesel 6 headed to North America: It produces 400 hp and 445 lb-ft of torque while remaining 51 percent stock by parts count.

Like the Cummins Diesel Special, the diesel 6's world debut wasn't exactly a stunning success -- Mazda failed to finish at Daytona in January. But the car has gone a long way toward proving itself since then, with class victories at Road Atlanta, Detroit, Mid-Ohio and the Watkins Glen Six Hours. We'll see how the team fares at Indy this weekend.

Oh, and lest you mistake the 6 for a single-seat Cummins-powered Indy racer, Mazda includes this helpful disclaimer in the press release:

“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.”

We really appreciate the honesty, Mazda -- as much as we really appreciate the new 6.

By Graham Kozak