Mazda Spent A Decade Engineering The Perfect Diesel, It Went So Badly Mazda Only Sold It For A Year

In 2019, Mazda finally achieved what it spent several years trying to perfect. The marque known for its stylish, fun-to-drive cars created the CX-5 Skyactiv-D diesel crossover. It seemed great on paper, but Mazda found itself in a pickle. By the time Mazda finally got a diesel on the American market, Volkswagen already sealed diesel’s fate as an unpopular fuel. Mazda wasn’t helped by the fact that buying the much more expensive diesel netted you a weaker engine that didn’t do that great on fuel economy. Mazda was so proud of its diesel effort that it even announced a diesel sedan. Instead, Mazda’s diesel would last just a year before its cancelation.

Welcome back to Unholy Fails! For a while, I’ve been showing you different cars and motorcycles throughout history befitting the moniker “Holy Grail.” Sometimes, an automaker tries to make a vehicle that would have had a shot of one day being considered a Holy Grail, but for whatever reason the vehicle ended up a dud. I should note that these aren’t necessarily bad cars. An Unholy Fail can be a great car, but one that ultimately failed to accomplish its mission.

I feel as if today’s nomination fills that role. Mazda didn’t necessarily make a bad car, but an expensive one that came far too late to matter. The Mazda CX-5 diesel was so late to the diesel game and came so long after the infamous Dieselgate scandal that it looked like an oddball in a sea of evolving EVs and hybrids.

However, Mazda’s original intent to get into the American diesel passenger car market wasn’t a foolish one.

This story takes us back to the late 2000s when Volkswagen was showing considerable success in marketing diesel passenger vehicles to Americans. The brand had been selling diesel cars to Americans for decades, but interest was really taking off as Volkswagen marketed its “Clean Diesel” TDIs as the future of greener transportation. It also helped that Volkswagen TDIs got great fuel economy at a time when gas prices were high. Of course, Volkswagen would later be caught gaming emissions testing to achieve the TDI’s “cleanliness,” sparking the infamous Dieselgate scandal, but this was before all that came to light.

In 2009, Volkswagen reported that 81 percent of all Jetta SportWagen sales, about 40 percent of Jetta sedan sales, and 29 percent of Touareg sales were diesel models. By July 2009, Volkswagen was claiming 26 percent of all the vehicles that went home with VW customers were diesel-powered. And that wasn’t even the high point; Volkswagen diesels continued to gain momentum into the 2010s, all the way up to the Dieselgate revelations.

Naturally, other automakers saw Volkswagen’s smashing success and wanted a piece of the pie. I mean, 26 percent of total sales cannot be ignored. For some brands, including Mazda, Volkswagen’s runaway diesel success was the catalyst to develop efficient diesel models of their own. If only Mazda knew what it was getting into.

The Beginning

In 2007, Mazda announced its “Sustainable Zoom-Zoom” plan and created Skyactiv as the umbrella term for the future technologies to be developed under Sustainable Zoom-Zoom. As a brand known for building vehicles that deliver driving pleasure, the goals of Sustainable Zoom-Zoom were to develop diesel technology that cut down on CO2 emissions while retaining a high level of safety and the enthusiast-leaning driving experience Mazda wanted people to associate with the brand.

By 2011, the Sustainable Zoom-Zoom plan called for a 30% increase in fuel efficiency in global Mazda products by 2015. It also called for a 23 percent reduction in CO2 emissions in the same timeframe. Mazda also introduced a building block strategy, a plan where the automaker would gradually improve its existing technologies while introducing electric equipment into its vehicles. Mazda would start small with functions like auto start and stop and eventually snake its way to electric powertrains.

In 2010, Mazda laid down a roadmap of tech it was working on, from Green Car Congress:

SKYACTIV-G. A next-generation highly-efficient direct-injection gasoline engine that achieves a compression ratio of 14.0:1 with no abnormal combustion (knocking). The high compression combustion results in significantly improved engine efficiency, resulting in 15% increases in fuel efficiency and torque. Increased torque at low- to mid-engine speeds improves the driving experience. A 4-2-1 exhaust system, cavity pistons, multihole injectors and other innovations enable the high compression ratio.

SKYACTIV-D. A next-generation clean diesel engine that will meet global emissions regulations (Euro 6, US EPA Tier2 Bin5, and Post New Long Term Regulations in Japan) without expensive NOx aftertreatments—urea selective catalytic reduction (SCR) or a Lean NOx Trap (LNT)—due to a low diesel engine compression ratio of 14.0:1. The low-compression ratio results in 20% better fuel efficiency, Mazda says. A new two-stage turbocharger realizes smooth and linear response from low to high engine speeds, and greatly increases low- and high-end torque (up to the 5,200 rpm rev limit).

SKYACTIV-Drive. A next-generation highly efficient automatic transmission that achieves excellent torque transfer efficiency through a wider lock-up range and features the best attributes of all transmission types. It combines the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions. A dramatically widened lock-up range improves torque transfer efficiency and realizes a direct driving feel that is equivalent to a manual transmission; the transmission delivers a 4-7% improvement in fuel economy compared to the current transmissions.

SKYACTIV-MT. A light and compact next-generation manual transmission optimized for a front-engined front-wheel-drive layout. It features a short stroke and light shift feel. Size and weight is reduced significantly due to a revised structure, and fuel economy is improved due to reduced friction.

SKYACTIV-Body A next-generation lightweight, highly-rigid body (8% lighter, 30% more rigid) with outstanding crash safety performance. SKYACTIV-Body is a straight structure in which each part of the frame is configured to be as straight as possible. Additionally, a continuous framework approach was adopted in which each section functions in a coordinated manner with the other connecting sections. Weight is reduced via optimized bonding methods and expanded use of high-tensile steel.

SKYACTIV-Chassis. The SKYACTIV next-generation high-performance lightweight chassis balances precise handling with a comfortable ride feel to realize driving pleasure. Newly developed front strut and rear multilink suspension enable high rigidity and lightness (The entire chassis is 14% lighter than the previous version.)

In case you skipped past it: Mazda was seriously thinking outside of the box. The Skyactiv-G gas engine would be different from the norm by having very high compression while the Skyactiv-D would be a low-compression diesel engine. Both these ideas were part of Mazda’s relentless pursuit to create the ideal internal combustion engine. The automaker wanted to make sure its engines were the absolute best they could be before the automaker would transition into other technologies.

At the time, Mazda said it would have its next-generation diesel engine ready for production in just two years. In 2012, Skyactiv-D did debut as promised. The Skyactiv-D 2.2 engine was fitted into the CX-5 crossover and then the Mazda6 sedan. Those cars then began to find some success for Mazda. America was due to get the engine in 2013 for the 2014 Mazda6. However, neither of those vehicles was sold in America with the Skyactiv-D 2.2. What happened? Mazda hit a snag when it came to certifying the engine for stricter U.S. emissions.

In September 2013, Mazda delayed the Skyactiv-D until April 2014. Reportedly, Mazda couldn’t figure out how to certify the Skyactiv-D to be 50-state legal while also having the engine perform as customers would expect from a Mazda. In January 2014, Mazda delayed the Skyactiv-D again, with no timeline for its arrival.

At the time, Mazda was set on doing even better than Volkswagen. Back then, you could buy a Volkswagen diesel that didn’t need a NOx after-treatment system like diesel exhaust fluid (DEF) to be “clean,” but still needed diesel particulate filters (DPF). Mazda wanted its diesel to use no after-treatment system at all. The automaker designed the Skyactiv-D to have a low compression ratio of 14:1 and hoped that optimized combustion timing would take care of those nasty emissions. What Mazda didn’t know was that Volkswagen wasn’t playing with a fair deck.

Still, Mazda sent its engineers to do what probably felt like was impossible. They had to engineer an engine that would deliver Zoom Zoom-worthy performance and do so while producing the kinds of light emissions the state of California would love to see. From DieselNet:

“While Mazda understands its Skyactiv-D can meet emission regulation requirements without the use of a NOx after-treatment system, it was decided that further development is required to deliver the right balance between fuel economy and Mazda-appropriate driving performance,” said the company. “Further information on the program, including a timeline of launch for North America, technical specifications and fuel economy will be available at a later date, closer to launch.”

The diesel engine then reportedly went into a sort of development hell. In 2015, Mazda indicated to WardsAuto that it even focused on other products ahead of fixing its diesel emissions dilemma. Engineers in Japan prioritized the new Mazda MX-5 Miata and the CX-3 over fixing the diesel engine.

In 2015, Mazda also showed the first signs of raising the white flag on its persistence in releasing a diesel engine without an after-treatment system. Still, Mazda wasn’t just going to slap a DEF tank to the existing Skyactiv-D. The automaker knew how important the TDI brand was to Volkswagen and it wanted Skyactiv-D to be the same. Volkswagen was the European benchmark for how to make a diesel, and Mazda wanted to be the new benchmark. Why did Mazda care so much? As Forbes reported, Volkswagen managed to capture 75 percent of the American diesel car market. The scraps were being fought over by Audi, Chevy, Jeep, BMW, and Mercedes-Benz.

Then Dieselgate took the world by storm. Suddenly, all the engineers chasing the success of Volkswagen’s TDI technology learned the “Clean Diesel” tech’s true innovation was the way it cleverly fooled emissions tests, not its ability to actually reduce emissions. Practically overnight, Volkswagen’s cheating put a black mark on diesel cars. Some automakers continued selling diesels anyway, which is how Americans were able to buy diesel-powered Cruzes long after Volkswagen got caught, but the damage was done.

But Mazda carried on, and in 2017, the brand once again promised to put a diesel engine in one of its American models, this time accompanied by the California Air Resources Board (CARB) certifying a Mazda diesel engine. In 2019, Mazda finally pulled the covers off the Mazda CX-5 Skyactiv-D. It took Mazda about a decade to develop the engine and meet U.S. emissions standards, with part of the extended development time reportedly the result of new diesel engines facing higher scrutiny from authorities in the wake of Dieselgate.

Still, Mazda had an 8 percent take rate for the Skyactiv-D in Europe, Japan, and Southeast Asia. A 10 percent take rate was expected for America, or a modest 15,000 units. After a very long wait, Mazda finally delivered its diesel engine to US buyers in the CX-5. Reportedly, the Mazda6 Skyactiv-D was also on the table, but we would never get it.

It’s Complicated

So, how did Mazda finally do it?

According to WardsAuto, one of the changes was the engine’s compression ratio. Mazda originally targeted a compression ratio of 14:1, lower than a typical diesel’s roughly 16:1 ratio. Mazda didn’t totally hit that target, but did hit 14.4:1. Reportedly, Mazda was able to hit that compression ratio thanks to improved fuel-injection technology. The CX-5 Skyactiv-D is noted to have piezoelectric fuel injectors with multiple nozzles that change dispersal pattern depending on the situation.

NOx emissions reduction was a big deal for Mazda when the engine was announced. The automaker did not achieve its goal of no after-treatment. The 2.2-liter twin-turbo Skyactiv-D engine received AdBlue urea injection, a NOx storage catalyst, and exhaust gas recirculation. According to WardsAuto, part of the addition of AdBlue was due to Mazda’s testing revealing drivers with a heavy right foot produced excessive emissions. AdBlue was the cure.

All of this was good news because it meant America could finally experience Mazda’s diesel engine, but it came with some weird penalties.

The biggest problem was the diesel provided no real power benefit. Modern diesels are known for their torque, but Mazda’s Skyactiv-D was an odd one out with its 168 HP and 290 lb-ft of torque. These numbers were handily bested by Mazda’s 2.5-liter turbo four, which made 250 HP and 310 lb-ft of torque. This is where you might expect me to tell you the diesel at least made its torque down low in the RPM range. The SkyActiv-D motor made its maximum torque when the tach’s needle swung to 2,000 RPM – just like the gas engine. If anything, that makes the gas engine sound that much cooler.

What Mazda’s diesel did offer was fuel economy. The 2.5-liter turbo four, when equipping a CX-5 AWD, delivered 27 mpg on the highway and 22 mpg in the city. The diesel, which was only available in the top Signature AWD trim level, achieved 30 mpg on the highway and 27 mpg in the city per EPA testing. Mazda representatives said the engine should do better than the EPA numbers. Some outlets hit the EPA numbers while some, like Car and Driver, were able to squeeze 34 mpg out of the engine.

While the diesel engine did offer better fuel economy than its gasoline counterpart, the greater cost of diesel fuel ate into the fuel-cost reduction benefit of the diesel’s narrow fuel economy advantage. The other problem was the $4,110 markup SkyActiv-D power added to CX-5’s asking price, further inflated by the required Signature AWD trim package. A four-grand premium for a slower engine that would only very slowly pay for itself at the pump (if it ever did) was a big ask – and the antithesis of zoom-zoom.

The CX-5

The SkyActiv-D was fitted into the Mazda CX-5, a compact crossover that Mazda has been selling since 2012. Here’s how Mazda describes the origins of the CX-5:

In 2010 when Mazda unveiled the Shinari—a four-door sports coupe concept—it also revealed its new “Kodo—Soul of Motion” design direction. The marque incorporated this styling into its next concept, the Minagi compact crossover SUV, which also brought Mazda’s suite of Skyactiv technologies to the public’s attention. The award-winning Mazda CX‑5 followed soon after, debuting at the September 2011 Frankfurt Motor Show. Combining both Kodo and Skyactiv attributes, the vehicle set out a new blueprint for the company’s future.

“Creating an SUV that would appeal globally was a difficult task,” recalls Masashi Nakayama, General Manager of Mazda’s Design Division, who styled the original CX‑5. “We set ourselves the challenge of bringing sporty design elements to the SUV, and in doing so created a whole new segment for the SUV market. We call this the ‘CX-5 segment’.”

From battling the elements in Chile to exploring Vietnam on and off the beaten track, the CX‑5 has proven it can handle any terrain. In 2019 a fleet of CX‑5s set off from the UK, traveling through ice and snow to reach Nordkapp, the northernmost point of mainland Europe. The CX‑5 has also crossed the world’s oldest and deepest lake—the frozen Lake Baikal in Siberia—becoming the first car manufacturer to achieve this feat. More recently, the CX‑5 excelled in a 62,000-mile endurance test conducted by German magazine Auto Bild, achieving one of the best marks ever awarded and earning a fourth-place spot in its all-time rankings.

The second-generation CX-5 launched in 2017 and was an evolution of Mazda’s Kodo design language. Mazda slots the CX-5 into the premium segment of compact crossovers and in my experience, it means rather lovely interiors with upscale appointments and features. In my experience, Mazda’s crossovers felt more expensive than they really were and kept you comfortable with low wind noise, good handling, and a suspension that soaks up the Midwest’s worst.

Reviews of the gasoline-powered CX-5 suggest the crossover’s independent suspension gave the vehicle agility and the CX-5 had decent body control. Opting for the Signature trim (again, a requirement to get the diesel engine), netted you Nappa leather, real wood trim, dual-zone climate control, heated and cooled front seats, a heads-up display, a 360-degree camera, and more. A “premium” vehicle, something really nice, but not quite luxury. I love it. Also, getting the diesel bumped your towing capacity up from 2,000 pounds to 3,500 pounds, which isn’t much, but at least it’s something.

Reviewers weren’t very impressed with the diesel. In a review hosted by Motor Trend, a reviewer describes an experience that sounds like an old-school diesel with lots of turbo lag:

It’s worth noting that the diesel’s extra 209 pounds—as compared with a CX-5 Signature with the 2.5-liter turbocharged four-cylinder gas engine—does make itself felt in the steering, which seems a bit heavier than the standard model’s. It’s probably enough to make itself felt in corners, though I can’t say for sure. Southeast Michigan’s one fun cloverleaf on-/offramp has been under construction for what seems like years now, and the only kind of fast cornering in my month with the diesel Mazda was either around 45-degree city grid turns, or on a couple of very mild sweepers Up North.

Even those sorts of corners are hampered in the CX-5 by the diesel’s turbo lag. After VW got caught in Dieselgate, turbodiesel dynamics reverted to their natural state, which means a good deal of lag before the impeller winds up and pushes the driver back in the seat. Make a turn from a side street into heavy traffic—onto Woodward Avenue, for instance—and you have to recalibrate your response to various size gaps. Be patient. This is not specific to Mazda’s diesel, with its 290 lb-ft of torque. In fact, the CX-5’s throttle tip-in feels about as responsive as the 443-lb-ft 3.0-liter diesel V-6 in the 4,916-pound Land Rover Discovery.

[…]

The Mazda diesel’s payoff does not come from massive fuel savings, though. This example is EPA-rated for 27 mpg city and 30 mpg highway, 3 mpg better in the city and none better on the highway than the base 2.5 AWD. Compared to the turbo AWD model, the diesel is up 5 mpg in the city and 3 on the highway. I’m used to turbodiesels that have a strong highway number, which means fewer refueling stops on road trips, a nice advantage in the middle of winter in the Great Lakes region.

Our friend Kristen Lee echoed similar thoughts in her review for Jalopnik:

The car is also very slow. I’d heard from a fellow journalist the CX-5 diesel had just enough power to get out of its own way, but even that seemed generous when I actually got to drive it. Pieces breaking off of Pangaea would probably win a drag race. Other cars with similar power figures—the Toyota RAV4, the Camry, the Cadillac XT4—all felt like they could blitz the CX-5.

[…]

I appreciate that the CX-5 diesel exists. Variety is nice, and this is a nice idea. Agreeable as a daily driver, it has an impressively quality interior, too. Also, props to Mazda for building a diesel car that, you know, doesn’t cheat. (We think.)

But I also can’t shake the feeling this car sort of missed the boat. Had it come out 10ish years ago like it was supposed to, it probably would have had a fighting chance, since hybrids weren’t as prevalent and diesel’s reputation hadn’t been messed up beyond repair yet.

Kristen’s Jalopnik review and the review from Motor Trend note that the CX-5 indeed delivered on the promise of getting better mpg than the gasoline variants of the CX-5, but not that much better. Worse was the fact that if you really wanted good fuel economy, a hybrid did better. So, the CX-5 diesel found itself in a weird place. Mazda wanted buyers to pony up for a top-spec Signature and then pay another $4,000 for the diesel to get fuel economy that could be bested by a hybrid crossover running on regular gasoline. At the time, a Toyota RAV4 hybrid got 39 mpg for a mere $28,100.

It seemed like the Mazda CX-5 diesel was a fine crossover, but perhaps one that came a bit too late. If Mazda released its U.S. diesel in 2013 as expected and hit the originally estimated 43 mpg, it could have been a hit. Instead, it came at a time when diesel was already fading from American minds, and it didn’t bring much to the table. I couldn’t find any confirmed production numbers, but Motor Trend noted that Mazda corrected its sales expectations to just 1,000 units in 2019. The CX-5 diesel was discontinued after 2019 after slow sales, so that suggests that there aren’t many of them out there.

With that said, it isn’t hard to find one of these for sale. A quick search shows 11 for sale on a site like CarGurus and it looks like you could get one for about $24,000.

It’s incredible to think that Mazda spent nearly a decade tweaking an engine to sell it in America and in the end, its return on investment is perhaps as low as just 1,000 vehicles. So, that’s how Mazda made its own Unholy Fail. Still, it’s awesome Mazda even gave diesel a try and if you’re looking for a CX-5 that’s just a smidge different than the rest, the diesel could be your pick.