The Volkswagen Group and Mazda Motor were, a decade ago, triumphantly touting clean diesel technology that would in VW’s case eventually devolve into scandal, while for Mazda it proved merely an embarrassment.

The design here is quite delightful.

Both told us in 2009-2010 that smart engine controls and clever hardware would make it possible for drivers to buy a small, low-emissions diesel engine in economy cars like the VW Golf and Mazda3. The kicker: they would not need urea after-treatment to clean up tailpipe emissions.

VW quickly introduced turbocharged direct injection diesel engines (TDI) in a range of models, all over the world, leaving competitors amazed. At the Detroit auto show, I spotted a 2010 Golf TDI surrounded by admirers. Stenciled onto the door were the words Golf TDI Clean Diesel. VW was triumphant; buyers flocked to showrooms.

Mazda, on the other hand, had no diesel to offer then and for years to come. Mazda’s engineers could not make the diesel technology work, as hyped and promised.

The thing is, VW couldn’t, either. But rather than do the right thing and delay introduction, the German automaker went rogue.

The rear view.

From 2009-2015, VW perpetrated a grand hoax. The giant German automaker delivered some 11 million “clean diesels” that dodged emissions standards and testing thanks to programming software that activated only during laboratory testing. In real world use, these diesels were spewing up to 40 times more NOx or oxides of nitrogen than legally allowed. The “defeat device” was the secret to cleanliness without a urea after-treatment.

It was cheating on a global scale and VW was caught red-handed thanks to some savvy testers who smelled a rat and aggressive regulators, particularly in California.

To date, so-called “Dieselgate” has cost VW more than $30 billion (US) and counting. We can only hope that prosecutors find the courage to jail the executives and engineers who perpetrated this crime.

Here, our lax federal government is finally charging VW with importing cars into Canada that company executives knew violated emissions standards. VW is expected to plead guilty, as it did to similar charges in the United States in March 2017. The U.S. Government fined VW more than $4.3 billion US and part of the settlement included buybacks of offending cars and VW’s commitment to establish an electric vehicle charging network in the U.S.

Mazda’s well-conceived cabin.

This brings us to Mazda. While VW was cheating, Mazda was honest about its failure to engineer a small, clean diesel on a tight timeline. At the 2010 New York auto show, Mazda said it would launch its new Sky-D diesel engine in 2012. It was a bold announcement, one on which Mazda failed to deliver.

Mazda said its new, small diesel engine would be amazingly fuel efficient – better than a mid-size gasoline-electric hybrid – and it would beet the toughest emissions standards in the world. The secret: Mazda’s proprietary catalyst technology would make it possible to meet emissions rules without urea after-treatment.

Mazda, however, could not make the technology work properly and at a reasonable cost. So rather than cheat like VW, Mazda postponed its diesel launch. Again, and again.

Regularly through the mid-2010s I would ask Mazda types about the promised launch of this fabulous diesel and I was told it was coming. One very senior executive, exasperated, eventually told me to stop asking because he could no longer say honestly when the diesels might go on sale.

Driving a diesel will save you at the pump.

This brings us to 2019. Seven years after the promised launch, Mazda finally has for sale a modern, efficient, compression-ignition diesel. Alas, this is just as the popularity of oil burners is in steep decline.

Diesel once accounted for about 50 per cent of all passenger car sales in Europe, but fell to 36 per cent last year, notes The Financial Times, which adds that in the wake of the VW’s malfeasance, “manufacturers from Volvo to Nissan have vowed to phase out the fuel type” altogether.

Felipe Munoz, auto analyst at Jato, told The Financial Times, “The future demand of diesel will depend on how fast the electrification takes place.” Diesels in small cars will likely “die out faster” as electrification takes hold, though “the electrification of SUVs (sport utility vehicles) has proven to be more complicated, and diesel is still the main choice among some subsegments, so they might still have significant demand in the coming years.”

Perhaps. The Financial Times notes that small diesel car registrations in Europe fell to 468,856 in 2018 from 825,591 in 2015. Diesels apparently make the most sense now and in the immediate future for use in SUVs, like Mazda’s CX-5.

Mazda’s infotainment controller is well done.

Which bring us to the new CX-5 with Mazda’s SkyActiv-D 2.2-litre turbodiesel oil burner. It’s a compression-ignition alternative to Mazda’s 2.5-litre turbo gas engine which up to now has been the top engine in this compact SUV, standard in the Signature version.

The Sky D sans a spark plug may not boast tremendous horsepower (168 vs 250 for the gas), but torque is magnificent (290 lb-ft at a very low 2,000 rpm). The CX-5 diesel responds with authority when you punch the throttle; it’s not a jolt, like the gas turbo motor. The feel of the diesel is immensely satisfying. But note: this Mazda diesel requires urea after-treatment — AdBlue. Promise unfilled.

Moreover, the diesel is tow-rated at 1,586 kg (3.500 pounds) versus 907 kg or 2,000 lbs for the gas version. Yes, the gas turbo is quieter, but the diesel clatter of the Sky D is not intrusive.

Transport Canada says the SkyActiv-D CX-5 scores 7.9 litres/100 km for highway fuel economy, which is the same fuel economy rating you find for the non-turbo 2.5-litre CX-5. Let me assure you, however, that in the real world, the diesel CX-5 will achieve better fuel economy than any gas counterpart.

You may find pricing an issue. The SkyActive-D CX-5 lists for $48,031. It’s lavishly equipped CX-5 Signature model, though more expensive than its gas counterpart ($43,031). Both are lovely, lively little SUVs with everything from leather upholstery to a fine sound system, G-Vectoring Control and all the driving nannies you could want.

A strong diesel, but not precisely what was promised for 2012.

As for a comparison between the two powertrains, the diesel is more efficient than the gas and will save you $200-plus a year at the pump, notes Natural Resources Canada. The CO2 ratings are a wash, but the diesel’s smog rating is 1. This points to more smog-forming pollutants from the tailpipe, while the gas turbo is a 7 (on a 1-10 scale where 10 is best, 1 is worst).

Timing in life is (almost) everything, though, and when you miss the mark by seven years, well, what looked like a bold inspiration now has the appearance of an iffy proposition.