Life in petrol yet
Mazda 3 SKYACTIVE-X
Reports of Internal combustion’s demise have been greatly exaggerated, or so it seems. While electric propulsion might seem like the way forward, the actual take-up in most markets is barely above negligible, infrastructure is fractured, and though some advancing economies such as China are moving ahead with zeal on electric, that’s because it is a nation poor in oil and rich in coal. Therefore hardly a denizen of zero carbon emissions. To use a broadcasting metaphor, if the aim of widespread electric propulsion is to be the equivalent of digital streaming, right now we’re on Laserdisc.
Enter Mazda with an alternative future. But it looks just like the new Mazda 3, you say. Yup – except this handsome mediumsized hatch is powered by a Spark Controlled Compression Ignition petrol engine with Mild Hybrid technology. From 2.0 litres (‘rightsized’ rather than down-sized, and with no forced induction) it produces 179bhp, for 0-62mph in 7.9sec and a top speed of 134mph. Not bad for a £25k family car. It’s quiet, revs keenly, and suits the 3’s zippy yet supple chassis to a T. Overall, the Mazda 3 Skyactive-X is a well-made, stylish and likeable alternative to a VW Golf – one that claims 96g/km and 43mpg.
Think back to the SPCCI moniker: ‘compression ignition’. This is the clever bit. Forecasts reckon that, even by 2035, 85% of cars worldwide will still be powered by internal combustion engines. Sure, a greater proportion of them will be hybrids and plugins, and they’ll likely employ more energy recuperation. It’s also likely that internal combustion will work in ways different to how it does now. Such as in this engine.
At 14:1, its compression ratio is significantly higher than any other production petrol engine’s, yet also lower than the typical diesel’s, the frictional losses of which it avoids while yielding greater torque and up to 30% greater efficiency than spark engines. Significantly, it avoids the unburnt fuel problems of experimental homogeneous charge compression ignition engines, yet also avoids the higher nitrous oxide outputs of spark engines. And it’s stable at all engine speeds, right up to 7000rpm.
Mazda wheeled out Dr James Turner of Bath University’s Institute for Advanced Automotive Propulsion (basically, he’s Professor Engine!), who said: ‘We didn’t think it would be possible to make an engine like this yet.’ Key to its success is that, while it begins with conventional spark ignition, as it reaches optimum temperature, so only a tiny amount of injected vaporised fuel is ignited by a spark, the effect of which is to cause such high compression and temperature that the rest of the ultra-lean fuelair mixture combusts.
A final thought. By 2035, the motor industry will have to build four internal combustion engines
to satisf y world demand. There’s no way current electric vehicle production could keep pace with that.