It was not the end to the three-year Mazda diesel engine program the manufacturer hoped for: A 30th and 31st-place finish in the TUDOR United SportsCar Championship’s Petit Le Mans at Road Atlanta.

The program began with the one-and-done season in the Grand-Am GX program, then progressed into two years of racing the SKYACTIV diesel engine in the Prototype category, typically with two cars.

Early on in the Prototype program, it was apparent it would be a struggle to make the four-cylinder stock-block engine, designed to produce 155 horsepower, into a race engine that would approach 500 horsepower.

Now, with Mazda still having no diesel option for the Mazda 6 in the states, something promised since the program begun, coupled with low gasoline prices and the Volkswagen diesel debacle, this seems to be an excellent time to pull the plug. According to Bloomberg News, though, the diesel passenger car engine may still in play for the U.S., though hopelessly delayed. Forty-five percent of Mazdas are diesel-powered in Japan, the most of any automaker there.

While the race team had hoped to transition to a gasoline engine this season, reportedly Mazda in Japan balked, and that transition occurs at the 2016 Rolex 24 at Daytona. But this month, testing begins in earnest at Sebring International Raceway with 12-hour race simulations. In use will be the latest iteration of the Mazda MZR-R engine, similar to the one used in the Mazda-powered Dyson Racing Prototypes in the American Le Mans Series, but considerably updated.

Drivers bid farewell

For the drivers, it’s a little bittersweet. But not so bittersweet any of them are willing to relive the diesel days.

Said Joel Miller: “It’s really quite poetic to conclude this chapter here. We got the first win for that diesel engine here at Road Atlanta in 2013 in the GX class. The development over the past three years has come so far. Hats off to David Haskell (head of SpeedSource’s engine department), Zach Lagrone (team strategist/engineer) and everyone in the engine shop to get to the limit of what this engine was capable of doing.”

“My pro career started with the diesel, so it’s going to be kind of sad to see it go away,” said Tristan Nunez.

“This year has been an incredible growing year for the team,” added Tom Long. “We’ve turned it to completing a bunch of races in a row, picking up a lot of momentum for next year and the team chemistry is really there. It’s a really huge element carrying into next year. We’ll take that new engine that we’re testing, we’ll take our team personnel and put together every little nuance together for a really exciting season next year.”