New car review: Mazda 3 X20 Astina Skyactiv-X Sedan
Clever combustion technology offers better performance and lower emissions for Mazda’s ever-popular small car.
Rumours of the imminent demise of the internal combustion engine have been doing the rounds for years, gaining momentum with the rise of electric vehicles.
But the arrival last year of Mazda’s innovative Skyactiv-X engine suggests there may be life in the old piston-powered dog yet.
While the name might sound like something out of a Bond film, Skyactiv-X is actually Mazda’s latest move in its ongoing efforts to develop the ideal internal combustion engine as part of its multi-solution focus on improving sustainability and reducing corporate emissions.
The X20 Skyactiv-X petrol engine made its debut in the Mazda 3 in August last year, followed a month later by its fitment to the top grade of the brand’s popular compact SUV, the CX30.
While Mazda has been slower to embrace electrification and hybrid technology than rivals such as Toyota, Mitsubishi and Hyundai, these Skyactiv-X models do now incorporate a new Mazda M Hybrid system.
Rather than drive the car, the latter uses a belt-driven integrated starter-generator and 24-volt lithium-ion battery to support the new engine’s fuel economy and performance gains.
The high-compression (15:1) Skyactiv-X engine features what the Japanese car maker calls Spark Controlled Compression Ignition (SPCCI), which enables the engine to switch between conventional spark ignition operation and a split fuel injection process that creates separate zones of fuel-air mixture in the combustion chamber.
The super-high-pressure injection system delivers a very lean fuel-to-air mixture in the combustion chamber during the intake stroke, after which a separate, richer core of atomised fuel is injected directly around the spark plug during the compression stroke.
A separate fireball initiated by the spark plug firing then provides the final push that causes the whole mixture to sustain combustion via compression ignition.
Think of it as being a bit like the compression ignition process used by a diesel engine, but unlike a diesel the Mazda engine uses a spark to “time” the start of the process.
To ensure stable combustion with these ultra-lean mixtures, the SPCCI combustion control system precisely controls spark timing, fuel injection, and incorporates an in-cylinder pressure sensor.
High volumes of air are delivered to the engine by what Mazda coyly call a “high-response air supply unit”, but which is essentially a belt-driven supercharger.
The point of all this engineering wizardry is to blend the best aspects of a compression ignition or diesel engine – namely fuel efficiency and torque response – with the smooth, high-revving performance of a petrol engine.
The results include improvements to fuel economy under a range of driving conditions, while CO₂ and NOx emissions are also reduced. A three-way catalytic convertor and petrol particulate filter are fitted to the exhaust system to further clean exhaust gases.
On test, our combination of urban commuting and spirited driving on country back roads returned a figure of 8.5L/100km, well above the claimed combined cycle of 5.5L/100km, which incidentally marks this as the most frugal model in the Mazda 3 range.
A more economical driving style should yield thriftier results but it’s worth noting that the new engine requires minimum 95 RON premium fuel, unlike the other 2.0-litre variants in the range which are satisfied with standard ULP but consume an extra 0.6 litres per 100km (combined cycle).
A combustion-system monitoring screen in the infotainment display shows that the engine runs in its most efficient SCCI mode a majority of the time, except during cold start/warm-up and under high load or wide-open throttle conditions.
At these times, the engine seamlessly switches back to conventional petrol engine operation with a slightly different engine “note” the only clue to the trickery occurring beneath the bonnet.
From inside the cabin, operation feels both smooth and very refined, irrespective of combustion mode.
True to the engine’s design intent, there’s a healthy dollop of torque and good throttle response from low in the rev range and a willingness to continue delivering solidly as revs rise.
Mazda rates the engine outputs at 132kW with 224Nm of peak torque at 3000rpm, a bump of 18kW and 24Nm over the standard 2.0-litre engine.
A Sports mode for sharper powertrain response and paddle shifters for the six-speed auto adds a sportier dimension to the driving experience.
In all other respects the Astina holds true to what makes the Mazda 3 such a competent and popular small car.
As befits the top-spec model, it’s well equipped with plenty of nice-to-have features and all the latest in safety and advanced driver assistance technologies.
The lack of inductive phone charging is a notable omission that many rivals and even lesser models now offer.
Cabin space is good for a small car as is the sedan’s boot which, at 444 litres, offers an extra 149 litres of load capacity over the hatch.
Its crisp copybook is blemished only slightly by old-style gooseneck hinges intruding into the boot space, an absence of load tie-down points, and a space-saver spare.
The interior has a premium look and feel with plenty of soft-touch surfaces, stitch detailing and quality leather trim.
Road manners are equally classy with a confident and sporty edge to the steering and handling that makes it an enjoyable drive.
While Skyactiv-X is certainly an interesting step in the evolution of cleaner and more fuel-efficient engine technologies, only time will tell if it succeeds in extending the life of Mazda’s internal combustion engines.
There’s no denying the technology delivers enhanced performance and powertrain refinement which adds to the already strong appeal of Mazda’s excellent small car.
But the technology comes at a premium, stretching the budget an extra $3k over the identically equipped 2.5-litre petrol four-cylinder powered G25 Astina.
That pushes the price of the Mazda 3 Astina Skyactiv-X beyond the psychological $40k barrier, which is pricey for a small car.
It also brings into consideration the fact there are several other small hybrids available that offer superior fuel efficiency and lower emissions.
ENGINE: 2.0-litre Skyactiv-X petrol 4 cylinder
ANCAP CRASH RATING: 5 stars (2019)
FUEL CONSUMPTION (combined cycle, litres/100km): 5.5 (132g/km CO₂)
FOR: Engine performance and refinement, road manners, premium look and feel, space.
AGAINST: Price, requires premium fuel, space-saver spare, lacks inductive phone charging.