Mazda3 SKYACTIV-X 2019 Review – International

Has Mazda singlehandedly done what the rest of the world’s car-makers and their engineers couldn’t, or is it fighting a lone battle?

It’s a question at the core of the Japanese firm’s new SKYACTIV-X technology, which essentially marries the efficiency, torque and response of a diesel with the high-revving nature and output of a petrol.

Mazda’s highly-vaunted engine will arrive in Australia from year’s end in the new Mazda3 SKYACTIV-X, seemingly beating automotive behemoths including Mercedes-Benz and General Motors to the punch.

In due course, Mazda will introduce SKYACTIV-X to other new-generation models, most immediately the forthcoming CX-30 SUV.

Not only has SKYACTIV-X required substantial four-year investment from Mazda at a time where other car-makers are pushing heavily towards electrification, it doesn’t deliver revolutionary fuel efficiency on paper.

It’s much more subtle, about a 20-30 per cent claimed fuel saving: paring back the official NEDC claim to as little as 4.5L/100km in the Mazda3 hatch.

Power is likewise pedestrian given the technology and development at play. The 2.0-litre supercharged petrol four-cylinder makes 132kW at 6000rpm and 224Nm at 3000rpm.

By way of comparison, the new SKYACTIV-X generates more herbs than the current 2.0-litre engine (114kW/200Nm) but doesn’t have as much muscle as the 2.5-litre engine (139kW/252Nm).

But there is a bigger game at play here: emissions. In Europe, where stringent 95g/km CO2 fleet-average emission targets will be phased in from 2020, SKYACTIV-X crucially introduces emissions as low as 96g/km CO2, compared with 144g/km for an equivalent 2.0-litre petrol engine without the technology.

It means SKYACTIV-X will complement Mazda’s stated plans for plug-in hybrid and electric powertrains in the future.

A senior engineer within the Mazda development program reveals there was no Eureka moment in approving SKYACTIV-X for mass-market use, but rather, a firm commitment to get the technology right when it began investment in 2015.

Short of pulling out the whiteboard and formula sheet, as was the case during the international launch in Germany this month, SKYACTIV-X is an extension of the DiesOtto cycle that dates back at least two decades.

Whereas petrol engines rely on spark ignition, using a spark plug to ignite pre-mixed fuel and air inside each cylinder combustion chamber, diesel engines require combustion ignition, where fuel is injected into pre-compressed air in order to replicate the heat and pressure produced by a spark plug.

Diesel is more energy-dense than petrol, which naturally means more air and less fuel goes into the combustion chamber, making for better fuel economy. The downside is that diesel emits higher levels of particulates that can cause pollution.

SKYACTIV-X employs what Mazda calls Spark Controlled Compression Ignition (SPCCI). Running on petrol, spark is used to ignite a small, dense amount of the fuel-air mix in the cylinder, with a low-capacity supercharger and higher compression ratio (16.3: 1) raising the temperature and pressure so that the remaining fuel-air mix ignites under pressure like a diesel.

The engine also features a belt-driven ISG (integrated starter generator) which charges a 24-volt lithium-ion battery pack during deceleration. The battery is flat-packed into the vehicle’s floor structure (in part necessitating the new Mazda3’s 25mm wheelbase stretch). Recovered power stored in the pack is then used to boost performance.

Mercedes-Benz tinkered with the SPCCI in a 2007 S-Class concept, but this is officially its first mass-market application. The German car-maker’s emission-saving technologies are more present in hybridisation.

Mazda assures us the SKYACTIV-X engine – the X denoting the synergy of petrol and diesel technologies – will be subject to the same 10,000km/12-month servicing intervals as its regular petrol engines, and it doesn’t foresee any changes to long-term durability.

In fact, so streamlined is SKYACTIV-X that Mazda has integrated the technology onto its existing Mazda3 production line. Officials say SKYACTIV-X is cheaper to produce per engine than its current turbo-diesel engines, however, the new technology will command a premium when it goes on sale in Australia to help recoup four years’ worth of investment.

Just how much of a premium SKYACTIV-X commands remains to be seen, but it won’t be particularly cheap. carsales understands Mazda will only offer SKYACTIV-X in the flagship G25 Astina automatic grade ($38,000) – meaning there’s every likelihood it will chime in about $40,000 (plus on-road costs).

The other caveat here is that SKYACTIV-X technology requires a minimum 95-octane premium unleaded. Given that 95 RON PULP commands a circa 20 per cent pricing premium in Australia, the actual consumer cost saving of SKYACTIV-X is questionable.

The Mazda3 seems a fitting first application for SKYACTIV-X. The relatively modest 132kW/224Nm SKYACTIV-X engine outputs appear more than a match for the hatch’s 1350kg kerb weight.

And Mazda has pushed its best-selling passenger car upmarket in the current model cycle; so adding more range at the upper end of the model mix is hardly a massive deviation.

In any case, depressing the 3’s starter button elicits a familiar yet largely unremarkable sound from the engine bay as the starter motor fires the petrol four-cylinder to life.

At idle speed, the sound and vibration of SKYACTIV-X feels largely comparable to Mazda’s regular petrol engine; perhaps a slight improvement. The engine builds moderately pleasing low-end torque, gently cycling through its ratios (six-speed manual or automatic) out of intersections and roundabouts.

The assistance of the supercharger and mild-hybrid system are likewise benign in around-town driving. There’s no tangible surge or electronic assistance to speak of, but it’s a nice point of difference from the wooden-braking, whirring progress of a modern hybrid.

The seeming simplicity of the technology in practice is the SKYACTIV-X engine’s charm and the transition between spark ignition and compression ignition is virtually imperceptible out on the road.

A live graphic within the Mazda3’s centre infotainment screen projects when either cycle is in use, but it changes so frequently depending on throttle input that it soon becomes a distraction.

Building speed higher into the rev range, SKYACTIV-X again retains the traditional sound and vibration harshness of a regular petrol, albeit with an added air of refinement.

There is one exception, however: with the engine up to speed and spinning under light load, burying your right foot (for an overtaking manoeuvre or similar) triggers a diesel-like clatter from the SKYACTIV-X unit.

It’s brief, about one second in duration, and the sound is only faint – but the noise does detract slightly from SKYACTIV-X’s positioning as a flagship engine.

On the flipside, the biggest advantage is felt in the higher echelons of the rev range, from about 4000rpm onwards. Here, it gains a noticeable second wind, pulling hard until the circa-7000rpm cut-out. But how advantageous that is in daily driving is questionable.

The matching soundtrack closely resembles that of a traditional petrol engine; never thrashy or raucous, but perhaps not the whisper-quiet and smooth passage that Mazda’s marketing rhetoric suggests.

Does Mazda’s SKYACTIV-X engine tech rewrite the rules on internal combustion? The truth is that it will take more than a 30-minute lap of the block to ascertain whether Mazda has uncovered internal combustion’s silver bullet.

Japanese engineers openly concede they are only at the beginning of the SPCCI journey, and expect to make marked improvements in the years ahead.

We can safely say this isn’t the petrol engine’s game-changing moment. But what SKYACTIV-X does do is make the humble internal combustion engine more efficient, more environmentally friendly and more socially responsible at a time when EVs remain too expensive and restrictive for the masses.

With combustion engines expected to power the majority of vehicles for many years to come, SKYACTIV-X will the buy the ICE more time -- particularly in CO2-obsessed Europe – and should have a significant impact on Mazda’s total emissions, both on its own and in concert with electrification.

As we arrive at the coal-face of the all-encompassing electric revolution, it’s refreshing to see there’s more life and relevance in internal combustion yet.

How much does the 2019 Mazda3 SKYACTIV-X cost?
Price: $35,000-$40,000 plus on-road costs (estimated)
Engine: 2.0-litre four-cylinder supercharged petrol
Output: 132kW/224Nm
Transmission: Six-speed manual and automatic
Fuel: 4.5-5.3L/100km (NEDC)
CO2: 103-120g/km (NEDC)
Safety rating: Five-star ANCAP