With Volkswagen out of the diesel engine business, are fuel efficient diesel cars doomed?
Chevrolet doesn't think so, as it's now offering a wide range of diesel models, including the small Equinox SUV and compact Cruze sedan or hatchback. Adding in the Silverado and Colorado pickups, Chevy has a total of four models with optional diesel power.
And when Mazda debuted the current CX-5 SUV at the L.A. Auto Show in November 2016, they said it would be available with a diesel engine called Skyactiv-D, currently sold in other markets.
No sign of Mazda's diesel 14 months after it was promised, but since then they've announced an engine breakthrough of another kind. It's a new type of gasoline engine with diesel-like mileage and diesel-like power.
"The efficiency is very similar to what you get with a diesel - the fact that it tends to be very strong at low RPM, and has great torque. But then the strengths of the gasoline engine, it keeps making power at higher RPM, and it's more quiet and smooth," said Dave Coleman, an engineer at Mazda R&D in Irvine.
The key is very high compression, almost like a diesel. Other automakers have tried to create these for production cars, but couldn't get the formula right.
Mazda is employing a system that measures pressure in the combustion chamber, which then tells a microprocessor how to adjust the fuel and spark. This happens in literally nanoseconds, during each cycle of the engine.
I got to be one of a handful of people to drive a test bed car with the Skyactiv-X engine, as Mazda has called it, with an engineer riding in the passenger seat and monitoring things. There was no way to test the fuel economy (Mazda claims it's 20 percent more efficient than a gasoline engine), but the power is definitely there, especially at low engine speeds.
"Nobody's been able to get quite the level of refinement, and to work really smoothly under a wide variety of conditions until now. Mazda figured out the 'secret sauce' with their spark control system," said Sam Abuelsamid, an auto analyst for Navigant Research in Ann Arbor, Michigan. Abuelsamid was also among the invited guests who drove the prototype car.
The new engine includes lots of other tech. There's a small supercharger, and a mild belt-driven hybrid system on board to help a vehicle operate smoothly, particularly when moving away from rest.
Mazda says the Skyactiv-X engine is still about two years away from production, and they've filed multiple patent applications on the design. It's safe to say that they would use the technology across their entire product line of vehicles. They also confirmed that their Skyactiv-D diesel program is still going to come to market.
So the two technologies could exist side-by-side. And this revolutionary gas engine could also pair well in future hybrid applications. Mazda is now partnered with Toyota, the leader in that area.
They're not making any announcements about future vehicles with battery plug-in or hybrid power, but as the entire auto industry moves toward electrification, that would seem inevitable.
"If we make a hybrid car, a hybrid still has a gasoline engine in it. So you want to make sure that gasoline engine is as efficient as possible, so that the hybrid system is as efficient as possible," noted Dave Coleman of Mazda R&D.