Like a science experiment brought to life, Mazda's Skyactiv-X points to an ongoing petrol-driven future – and does so quite convincingly.
As a corporation, Mazda’s size and scope are but a fraction of behemoths like Toyota, Hyundai or Volkswagen, yet somehow the Japanese brand remains determined to tread its own distinct path.
That’s perhaps most evident in the new 2020 Mazda 3 X20 Astina Skyactiv-X M Hybrid. This car is the second stage in Mazda’s plan for a range of more sustainable products by 2030, and follows the regular petrol and diesel engines in the brand’s passenger cars, which were part of stage one.
Mazda doesn’t see a single path to creating more planet-friendly products, so has pursued multiple avenues to reduce vehicle emissions, not just at the exhaust, but at every stage from production onwards.
One of those solutions is called Skyactiv-X. It’s the name given to the petrol engine under the bonnet of the Mazda 3 X20, and it’s fascinating technology designed to prolong the lifespan of the petrol engine, rather than making a wholesale shift to alternatives like battery electric vehicles or hydrogen fuel cells.
Electrification isn’t off the table, though. In fact, the ‘M Hybrid’ part of the name is just that. As such, this new model is the first for Mazda Australia to include electrification, which is another pillar in Mazda’s second-stage enviro push.
So what is it, really? Well, the Skyactiv-X engine combines the free-revving nature of a petrol engine with the very lean running typically seen from diesels. Diesels don’t use a spark plug to ignite fuel – heat and pressure do that for them.
Mazda is the first to bring a compression-ignition petrol engine to market, and to do so it has added spark plugs. Sounds counterintuitive, but a true sparkless petrol engine has a limited operating range in theory.
Things like engine temperature and load (either too much or too little) disrupt a petrol engine’s ability to combust fuel under pressure. Running a very lean fuel mix also creates problems – the less fuel you have, the less likely you are to get it to all burn successfully.
To counter this, Mazda’s use of a spark plug varies depending on what the engine is doing. It can operate like a normal petrol engine and ignite fuel as the engine warms up, at idle, at high revs, or under load. When conditions allow, the Spark Controlled Compression Ignition (or SPCCI) running cycle uses precise fuel injection to create separate zones within the combustion chamber of each cylinder.
A lean injection of fuel runs in during the intake stroke. During the compression stroke, another injection around the spark plug is then lit by the plug, pressure increases in the combustion chamber, and the lean mix combusts.
In order to help it out, the engine uses an air pump to get more air in and increase the ratio of air to fuel. A supercharger is used for this purpose, though it’s not there to boost power – more to keep the engine from running out of the volume of air required to maintain a lean burn.
You might have heard the term ‘Miller cycle’ used on a Mazda-Eunos engine from the 1990s (then again you, may not have). The Skyactiv-X reintroduces Miller-cycle running.
This allows the intake valves to stay open longer than a traditional Otto-cycle engine would; the goal here is improved thermal efficiency. Toyota does something similar with Atkinson-cycle engines on its hybrid cars, though without a supercharger to lean out the air-fuel ratio.
As for the M Hybrid side of things, that’s Mazda’s implementation of a mild hybrid system. Brands like Mercedes-Benz and Audi have similar 48-volt mild hybrid systems already. Mazda uses a 24V system, defying the trend for 48V mild hybrids.
While Mazda is no stranger to idle-stop tech, available under the i-stop label in the current range of cars, the new system can do much more. It will still not only stop the engine when stationary, but also harvest kinetic energy while coasting to top up its lithium-ion battery.
That harvested power can then be fed back to the engine via a belt-driven integrated starter generator (ISG), which not only allows faster, smoother engine restart, but can also chip in to assist the engine in some conditions.
It isn’t quite the same as a Toyota hybrid. The Mazda can’t run on electricity alone, even at low speeds or for short distances, but the ISG provides a helping hand with outputs of 4.8kW and 60.5Nm.
Overall, the system claims 132kW at 6000rpm and 224Nm at 3000rpm. Unlike a turbo engine, maximum torque isn’t available just off idle, but like most supercharged engines it builds in a linear way as revs rise.
The all-important official fuel claim is 5.5 litres per 100km when paired with a six-speed automatic, or 5.3L/100km with a manual. Yes, that’s right, a manual is available, though as with the regular Astina range expect the auto to rule supreme, so I’ll focus on it.
Against the ‘normal’ Mazda 3 automatic, the X20 is the most frugal, but not by any kind of landslide. G25 models fitted with a 2.5-litre naturally aspirated engine are rated at 6.5L/100km, while the smaller G20 engine, a 2.0-litre naturally aspirated unit, claims 6.1L/100km.
The ground-breaking 2.0-litre Mazda 3 X20 Astina isn’t quite up to the standard of something like a Corolla Hybrid, which lists 4.2L/100km for the hatch or a staggeringly low 3.5L/100km as a sedan.
Not always the focus of attention in Australia, but CO2 emissions also drop, from 152 grams per kilometres in the 2.5-litre engine to a claimed 135g/km.
It's not efficient enough to offset its price difference. At claimed consumption, the X20 engine would save around $182 per year in fuel costs (at $1.40 per litre) for owners who travel a national average of 13,000km per year. If the price of fuel were to remain static (of course it won't) that's almost 16.5 years to even out the price difference.
It’s not that the Mazda isn’t efficient, though, it is, but perhaps labelling it a hybrid so proudly was a misstep. Worth noting, too, there are no hybrid badges on the Skyactiv-X cars – that’s a term saved for marketing materials.
In fact, the only outward sign of the technology within is a subtle Skyactiv-X badge on the rear of the car. Everything else, wheels, grille, headlights, interior, is exactly as you’ll find in a normal Mazda 3.
For this reason, I’ll break with tradition and not dissect the interior space, comfort and features. We’ll do that when the Mazda 3 comes back through the CarAdvice garage. Until then, you can click here to check out our past coverage, but for a broader view, those areas will still be scored at the bottom of this review.
The focus of the quick intro on Australian soil has to be the drive, with only an hour or so spent with the car. What are you getting if you opt for the X20 Astina instead of the G25 Astina?
For one thing, less power and torque. The 2.5-litre engine is rated to 139kW at 6000rpm and 252Nm at 4000rpm, putting it 7kW and 28Nm ahead of the new flagship engine.
There’s no doubt the X20 has a technologically superior engine, but is the $3000 step up a logical one for Australian new-car buyers who aren’t rewarded for choosing a low-consumption/low-emissions option? Keep in mind, Toyota asks just $1500 more to step from petrol to hybrid Corolla, which makes the Skyactiv-X value equation rather shaky.
There’s more to it than just on-paper figures. Skyactiv-X is a flagship engine, and while that may not mean peak performance, it has a noticeable impact on refinement. So…
NOTE: A number of photos in this review are of the regular Mazda 3 Astina, due to photography conditions surrounding the drive program.
From first start, there’s really nothing to separate the Skyactiv-X from its Skyactiv-G cousins.
It’s perhaps a touch quieter, maybe. Worth noting, though, Mazda had warmed up the engine ahead of my arrival, so there was no opportunity to check for any signs of a coarse cold start.
One of the infotainment screen displays can show how the car is running, with details if the i-stop system is ready or not, if power is going to the wheels or the li-ion battery (or both), if the ISG is assisting, and most interestingly if the engine is running on spark ignition or SPCCI.
It’s sure to be a novelty with new owners, but it certainly surprised me. I figured SPCCI would be somewhat fragile, only able to operate in perfect conditions when the car is holding a steady cruising speed, but too timid to do any heavy lifting.
That was very wrong. Spark ignition steps out from just above idle, and as you accelerate through traffic, the SPCCI cycle does most of the engine's running.
Exploring my curiosity, I floored the accelerator from a few standing starts. Same results: spark, SPCCI, then as the tacho needle headed towards the redline, back to spark as indicated by red (spark) and green (SPCCI) indicators.
Getting to 6000rpm was no problem, no staggering or stuttering at any point. No obvious change from one ignition source to the other. No hesitation, and no uncomfortable harshness – which can't always be said of Mazda's naturally aspirated engines.
Rolling acceleration usually takes place via compression ignition, too, and the infographic suggests the ISG is happy to help out there.
Mazda wasn’t able to confirm if there’s an upper speed ceiling at which the ISG will no longer assist, but anecdotally at least, it seemed happy to share the load up to around 80km/h. Ideal for most urban and fringe roads, then.
I didn’t see it feed any electric assistance at around 100km/h, but can’t conclusively say it wouldn’t. There are all kinds of operating parameters that could impact this.
Unlike Audi’s higher-voltage mild hybrid system, the Mazda can’t cut the engine while coasting at speed and maintain momentum via its ISG. If the car does coast, the engine keeps spinning, but the ISG, in generator mode, feeds power back to the battery.
The upscaled start-stop function is happy to step in more readily than on Skyactiv-G engines, which tend to require a more hearty shove on the brake pedal to confirm activation. For Skyactiv-X, once you’re stopped, so is the engine, if conditions allow.
Mazda has also made some tweaks to the six-speed automatic transmission, giving it a revised shift strategy for smoother gear changes and quicker downshifts. Hard to say how big an impact the changes made, but everything felt smooth and snappy on test.
As an aside, Australia only gets a front-wheel-drive version of the Skyactiv-X, as with the rest of the Mazda 3 range, but overseas markets also have an all-wheel-drive option. Buyers looking for all-paw grip in Australia will be able to opt for the CX-30 X20 small SUV, with the same new engine, due to hit showrooms from September 2020.
Far and away, the biggest difference X holds over G is refinement. Mazda has been on a mission with its more recent models and updates to stamp out unsavoury engine noise and vibrations.
The Mazda 3 X20 absolutely nails the brief. That’s not to say the regular petrol models are poor in this regard, but they can get a little raucous under load.
Early indications suggest the Skyactiv-X engine is better isolated. That’s quite a feat, too. The rattle you hear from a diesel engine is a symptom of compression ignition; it’s not the fuel that makes the noise, but the way it ignites.
For Mazda to be able to silence that potential noise source is impressive. There were a few times where the faintest rattle could be heard. Pinging, as it might otherwise be known, but with the radio on you’d never pick it.
There are some tractability gains, too. While peak torque may be less than the 2.5-litre engine, with electric assistance and the grunt of a supercharger, the 2.0-litre Skyactiv-X feels stronger at low-to-mid engine speeds.
Not performance car swift by a long shot, but more willing where it matters, without the need to wring out the motor to tap into its urge. All the better to keep things calm and quiet, too.
The X20 does ask to be treated a little differently to the G20 or G25, in that it requires 95RON premium unleaded, whereas Mazda’s other engines will happily accept 91RON regular unleaded. Chalk that up to this engine’s use of a GPF, a petrol (or gasoline, as Mazda calls it) particulate filter, which needs the lower-sulphur fuel to stay healthy.
As for consumption, against Mazda’s official 5.5L/100km claim, the sedan driven here returned 6.8L/100km, but it has to be said Mazda had nothing to hide here. The route it chose wasn’t an all-out economy drive with, apparently, 30 sets of traffic lights to catch the car out, and some elevation changes thrown in for good measure.
Again, we’ll run more figures down the track to see how this stacks up against competitors, and on different drive routes in a range of conditions, but the sub-seven figure is decent. It may not be as miserly as a full-blown hybrid, but on face value it stands up.
The elephant in Mazda’s room might be value. A regular Mazda 3 G25 Astina automatic is priced from $38,590 before on-road costs, the X20 Astina auto is $41,590, or if you’re after a manual knock $1000 off either price.
The step-up buys you extra tech, and if that’s what you’re into it’s justifiable. It doesn’t quite buy you the kind of green-boasting a Corolla Hybrid would, and that car keeps coming up because of the obvious hybrid association.
The h-word could be where Mazda has cheated itself a little. The Mazda 3 isn’t a hybrid, at least not as we know them, but the way the ISG motor assist works is convincing all the same.
Getting a combination of spark and compression ignition to play nicely is a technological feat that brands like Mercedes-Benz started talking about over 10 years ago, but haven’t delivered for consumers. What Mazda’s done here is impressive, but impressive for engineering boffins and perhaps harder to convey to customers.
To Mazda’s credit, the Skyactiv-X engine also packs in added refinement and the extra oomph. Those demonstrable capabilities ought to be the things that stand out on a test drive, and might just be enough to seal the deal on the X20 over the G25.
No doubt that like Skyactiv-G did initially, Skyactiv-X will spread through the range. And when it does, the positives it brings with it should stand Mazda in good stead.
The hard question Mazda has to face, and buyers might struggle to grasp: was it worth the effort?
The technology is intriguing, but it’s also possible to buy a Mercedes-Benz A180 hatch that uses just 0.2L/100km more fuel with a turbo petrol engine that – in theory at least – is much simpler, if not quite a perfect output match. More convincing still, the Volkswagen Golf 110TSI Highline is cheaper, comparably equipped, a little less powerful but with more torque, and 0.1L/100km more frugal than the Mazda 3 X20.
That's awkward for Mazda, then, isn't it? Millions of dollars of development, a range of unique engineering solutions, and an outcome bettered by a car that's been available for eight years. Ouch.
Where Skyactiv-X technology truly excels is in maintaining Mazda’s ethos of cars built for drivers. Cars that feel natural with reflexes and behaviours that mimic those of the human body. Free from clunking dual-clutch transmissions or sleepy CVT autos. Free from surging boost-laden turbocharging. Instilled with confident handling, engaging steering, and an agreeable linearity for the driver.
The Mazda 3 X20 Astina Skyactiv-X M Hybrid isn’t a green-car superstar, and it’s all the more entertaining for it. Electric vehicles might be the path of the future, but if the present is here to stay, Mazda’s attempt at prolonging the life of the petrol engine appears to have been worth the effort, if not the expense.
NOTE: A number of photos in this review are of the regular Mazda 3 Astina, due to photography conditions surrounding the drive program.