WHEN is a diesel not a diesel? When it’s a Mazda3 Skyactiv-X. Allow me to explain.
Mazda hasn’t followed the crowd by “downsizing”, the act of making a petrol engine smaller in capacity and then fitting a turbo to it.
Instead, it believes in “right- sizing” — having the correct capacity engine for the job so it is less stressed.
In Mazda’s case, that’s a 2-litre petrol. But, wait a minute; Mazda’s already got a 122hp, 2-litre Skyactiv-G petrol in the new 3. So what’s this one about?
Well, it’s the “X” bit that’s key. Mazda doesn’t like fitting turbos to petrol engines and so has engineered its 180hp motor to run like a diesel when it needs to.
That’s because it burns fuel by combustion, rather than using a spark (generated from a spark plug), although — confusingly — the full name for Skyactiv-X is Spark-Controlled Compression Ignition (SPCCI).
So confident is Mazda in this incredibly clever tech that it has killed off the 1.8-litre turbo diesel, which was available in the 3 hatchback from its UK launch last May.
This petrol emits just 109g/km of CO2, making it the tax-friendly, company-car choice.
It is also claimed to do 45.6mpg, which isn’t that impressive by diesel standards but then, this isn’t a diesel; it’s a 180hp petrol, capable of propelling the Mazda3 AWD as tested to 62mph from rest in just 8.5 seconds. Theoretically, it’s the best of all worlds. But does it work? In a word, no.
It is beautifully engineered, as everything from Mazda tends to be. And it’s a very smooth engine, allied to a fantastic manual gearbox that’s one of the best in the business.
But if you start thinking it will haul from low revs like a turbodiesel, you are going to be disappointed. Relatively speaking, the Skyactiv-X delivers more torque at lower revs than Mazda’s other non-turbo engines. Yet, compared to any of its key turbocharged rivals, it is a lot more dem-anding to drive.
On steep hills, you will be downshifting to second to keep going. Drop it below 2,500rpm and try to accelerate on the flat in a higher gear, and you’ll be left behind by other traffic.
Drive it moderately hard, and you can expect 32mpg from it — which is most emphatically un-diesel-like. Technologically, the Skyactiv-X is a remarkable engine. But it’s not the right motor for this car. Which, by the way, is one of the best vehicles in its class. It looks fabulous.
The interior is VW Golf- rivalling, there’s loads of kit across the board and it’s a comfortable, quiet thing to travel in. Turns out, then, that all we wanted here was a diesel that . . . was a diesel.
Because Skyactiv-X isn’t (yet) the answer.
MAZDA3 SKYACTIV-X GT SPORT TECH
Engine: 2-litre petrol
Power: 180hp, 224Nm
0-62mph: 8.5 secs
Top speed: 133mph