Skyactiv-X put to the test: is Mazda's new engine really the best of both worlds?
I put Mazda's unique Skyactiv-X engine to the test in the sleek Mazda3 Hatch to see if it really can combine the benefits of petrol and diesel engines into one.
Very rarely these days is an engine something that is the headline act when it comes to a new car. Normally, advanced safety equipment, next-level interior technology, and electrification commands all the attention these days, but an internal combustion engine? That’s something special.
The headline-stealing engine in question is known as Skyactiv-X and it comes courtesy of Mazda, which isn’t exactly that much of a surprise when you think about it – after all, it’d have to take a company like the biggest adopter of the Wankel rotary engine to try and reinvent just how a four-stroke engine works.
However, in typical 21st Century fashion, this evolutionary engine does come wrapped up in the skin of an ordinary and sensible hatchback and sedan combo – even if it is the extremely attractive Mazda3 twins first launched last year.
Badged as the X20 and offered solely in the top-spec Astina model, not much is done to shout about this intelligent new engine – a small Skyactiv-X badge on the bootlid and a unique driveline status display in the infotainment system are the only giveaways that anything is out of the ordinary here, and for the average buyer that’s obviously an important thing.
Now the 3 these days has been positioned by Mazda, like many of the company’s other offerings, as a premium on a budget sort of buy, and the model’s push upmarket is clear when it comes to this Skyactiv-X model as a starting price of $40,590 for the manual – which $1000 extra for the automatic transmission and $495 for the fabulous Polymetal Grey paint on my tester bumps the price up to $42,085 – means this thing sure ain’t cheap by non-hot hatchback standards.
Take a seat inside it though and the price tag certainly starts to justify itself. The materials are truly on the level of Lexus, the layout and presentation is beautifully minimalist and elegantly modern, and it’s not lacking in the way of any features at all.
Similarly, on the outside, it looks expensive as well. The hatch’s styling may be divisive in the eyes of some, but I’m a huge fan of it. Free of all hard body lines – with its curvaceous paintwork accented by the specially-designed Polymetal Grey hue you see here – it’s a very sophisticated design that, while introducing some compromises such as the reduced rearward visibility and smaller boot space, helps it truly stand out next to its rivals, all of which the 3 makes look a bit stiff and ordinary by comparison.
Now, does the truly luxurious interior and sophisticated exterior do enough to justify the price tag? To a point, yes, as it feels every bit a cut above its rivals in that regard, but it must be said that it’s still sticking out a fair way in front of the pack as far as pricing is concerned – especially once you factor in on-road costs that will drive that figure even higher.
However, such is the price one must pay to be an early adopter of new technology – and, of course, it’s that technology that’s the real drawcard here.
So, the Skyactiv-X engine – it’s a 2.0-litre supercharged four-cylinder petrol unit that makes 132kW at 6000rpm and 224Nm at 3000rpm, and has a 24V mild hybrid system tacked on as well to replace the traditional start-stop system along with allowing the engine to shut off at lower speeds when slowing to a stop.
Now, I know exactly what you’re thinking right now. No, those aren’t exactly groundbreaking numbers, but that’s not exactly the point of this engine. Looking at another number, its 15:1 compression ratio that’s enabled through unique piston and cylinder head designs, is more telling of why this engine matters – because it’s truly unlike any other petrol engine that has come before it.
The ignition system this engine uses is what Mazda dubs SPCCI – Spark Controlled Compression Ignition – and essentially bridges the gap between petrol and diesel engines, offering the benefits of both but drawbacks of neither in theory.
While a conventional petrol engine uses a spark plug to ignite the air-fuel mixture which gradually combusts within the cylinder during the piston’s downstroke, and while a diesel engine’s air-fuel mixture simultaneously combusts due to pressure and heat alone, the SPCCI system uses the spark plug to ignite a small, dense amount of the air-fuel mixture – which has been compressed at a much higher ratio than in a typical petrol engine – to raise the internal temperature of the cylinder which allows the rest of the mixture to ignite simultaneously due to pressure alone like in a diesel engine.
The result is that, like a diesel engine, it uses far more air and, as a result, is more energy-dense as less fuel needs to be used. It’s worth noting here as well that the supercharger fitted to this engine is used to help feed it more air at lower revs to allow it to run in this more energy-dense and efficient way, rather than to add power, although its aid can certainly be felt around 3000rpm at the peak of this engine’s torque curve.
To handle power at higher revs, though, this engine reverts to running like a conventional petrol engine above around 4500rpm to allow for the high-revving power petrol engines produce. As I said, it’s the best of both worlds, it would seem.
How does it feel in reality? Well, to the average punter, they probably won’t notice anything about it, other than perhaps its deeper tone and the fact it's generally quieter and more refined than the engines in other Mazda3 variants, which is effectively the point – to try and future-proof the petrol engine in a way that doesn’t alter it too drastically.
To the keener drivers out there, though, you’ll certainly be able to spot the difference once you start to focus on it. Unsurprising as this may seem, it does feel a bit like a diesel engine while utilising its compression ignition capabilities. That is to say, while it does feel torquey and has enough poke to get you around, it’s not exactly the most athletic-feeling engine you’ll come across. It’s torquier than the regular Skyactiv-G 2.0-litre petrol engine, no doubt, but far less free-revving.
That is, however, until you push it into the upper third of its rev range, at which point it really does feel to open up and while progress isn’t drastically hastened, it certainly starts to feel like a petrol engine once again. It’s a unique-feeling engine, certainly, but for someone like myself who enjoys nerding out over this sort of thing, I rather like it.
Now, it’s worth pointing out here that in every other sense it feels just like any other Mazda3 to drive as far as the ride and handling is concerned. It has a great chassis with a responsive and well-weighted tiller, an automatic transmission that’s smooth and pretty responsive, and a ride that feels to be nicely balanced between comfortable and sporty, and although the torsion beam rear suspension does help to keep road noise down – thankfully! – it does transfer through more road imperfections than the old model’s independent setup.
But enough about how it drives – there’s one all-important question here, and that’s just how much fuel this thing saves compared to a regular petrol engine, as that is the primary aim of this thing after all. According to Mazda’s claims, manual models will use just 5.3L/100km on the combined cycle while the automatic I had on test will use a claimed 5.5L/100km.
I spent my first few days with the car mainly pottering around in traffic, along with getting it out onto a few of my usual testing roads to enjoy and exploit its impressive chassis, and after around 250km of this, the number I was seeing on the dashboard was 7.3L/100km. However, after a weekend jaunt from Adelaide to Naracoorte and back, along with a further few days of city driving, that number was down to an indicated 6.6L/100km.
While this is certainly a big improvement over the 8.5L/100km return I saw when I tested the regular 2.0-litre Mazda3 last year, it does still leave this new Skyactiv-X model off the mark of cars such as the ultra-frugal Toyota Corolla Hybrid.
Although the afterthought 24V mild hybrid system I feel is somewhat to blame – only twice during the entire week I spent with the car did it actually even stop the engine at the lights – it just feels as though the SPCCI technology, while it certainly does save a good amount of fuel and present numerous other benefits of diesel engines in a petrol engine’s context, isn’t exactly the game-changer some hyped it up to potentially being.
However, I feel as though Mazda wasn’t exactly trying to change the game here. With the company acknowledging that electric vehicles are the way of the future, it views this technology as something designed to allow for leaner and greener petrol engines in the meantime until EVs do become mainstream, and as far as that objective is concerned, they’ve done it, along with also proving just how much potential is left in the internal combustion engine.
Furthermore, I feel as though this technology may work even better on higher-displacement engines, and with it having been rumoured for some time that Mazda has a 3.0-litre straight-six Skyactiv-X engine in the works for the next Mazda6, I think this tech may just allow Mazda to actually upsize at a time when most companies are making their engines smaller and smaller.
At the very least, while the tech may look to be a waste of development money to some, in the longer term I feel as though it’ll pay off for Mazda. After all, the automotive industry has been trying to figure out how to make compression ignition work in a petrol engine for decades, and that as small a company as Mazda has been able to pull it off at all is worthy of applause in my eyes.
This article originally appeared on drivesection.com on December 2, 2020. The vehicle tested here was provided by Mazda Australia. All noted prices are in Australian dollars (AUD).