MAZDA CX-60 3.3 E-SKYACTIV D
Admirably defiant Mazda creates an all-new straight-six diesel engine for its big SUV
The recently confirmed Euro 7 emissions regulations may have forced some investment here and there, but few firms seem to be doing proper research and development on brand-new combustion engines any more, clearly having other priorities.
Mazda, as ever, is different. It believes in a global decarbonisation strategy that makes room for ICES while there’s still call for them and while they can still be made more efficient. And as its new CX-60 3.3 e-skyactiv D clearly demonstrates, in the case of the bigger ones in particular, they absolutely can.
Mazda’s product renewal plan happens to have just delivered a new family of larger, longwaysengined SUVS: the CX-60 last year, the seven-seat CX-80 to Europe later this year and their CX-70 and CX-90 siblings to other global markets.
And because the markets in which those cars will be sold still have an appetite for petrol and diesel (Japan itself remains fairly
Bev-sceptical), they need new big engines to match, in addition to hybrid and plug-in hybrid options.
That’s how it is that the CX-60, which arrived in the UK last year in four-cylinder PHEV form, is now getting a box-fresh, 3.3-litre straight-six turbodiesel engine.
To European eyes, its appearance may seem a bit of an anachronism: an only mildly hybridised straightsix diesel in a mid-size, premiumprice SUV at a time when so many customers apparently wouldn’t contemplate spending lots on a car that didn’t come with a plug?
The answer, as Mazda has it, is pretty simple: in a car of this size, a six-pot diesel is actually cleaner and more economical than a four-pot.
As Heiko Strietzel – manager of the powertrain development team behind the unit – explains, a bigger engine can produce the torque necessary to cover most of the propulsive needs of the CX-60 at lower loads, revs and combustion temperatures than an equivalent four-pot. By applying an innovative new piston design and a fuel injection method called DCPCI (Distribution-controlled Partially Premixed Compression Ignition), that engine can more than offset the impacts of its greater mass, friction and swept capacity simply by remaining in a closely controlled, lean-burn state of operation for longer than a four-pot might.
“Because it can operate at better than 40% thermal efficiency for so much of the time, our research confirms that the 3.3-litre sixcylinder diesel engine is right
sized for the CX-60,” says Strietzel.
The car’s WLTP fuel economy and CO2 emissions lab test results would tend to confirm that when compared with those of the car’s four-cylinder diesel rivals.
Neat trick, eh? For Mazda’s next one, let’s hope for an atmo 7.3-litre petrol V12 that will do 150mpg.
The diesel will be available in two states of tune: 197bhp with rear-wheel drive and 251bhp with four-wheel drive.
Both variants use a new, Mazdadeveloped eight-speed automatic gearbox with a pair of wet clutches instead of a torque converter, plus a 48V electrical system that can contribute up to 113lb ft of torque to the driveline but tends only to boost the engine’s performance rather than drive the wheels all on its own.
There’s a distantly coarse chug about the engine’s audible character at idle, a little like a ferry leaving its harbour berth. But at cruising revs, it settles into smoother stride.
Mazda accepts that its leanfuelling calibration (which the engine adopts at crank speeds up to about 2200rpm and at up to about 250lb ft of load) does make the combustion sound a little more clattery than a typical modern diesel. It opted for that ‘perfect balance’ straight-six configuration at least in part to mitigate the issue.
The desired effect is mostly achieved. It revs quite freely up beyond 4000rpm, with generous and wide-spread torque. It’s quiet enough under light loads, too, and while there’s a bit too much digital engine noise synthesis, especially at full power, it’s still fairly rich and enticing to extend, and potentfeeling under your right foot.
The gearbox shifts smoothly and with intelligent timing, seemingly knowing when to hold a higher gear and when to drop it. It has a paddleshift manual mode whose shifts could be a little bit quicker but are certainly fast enough not to offend.
It’s a pity so much else about the CX-60 isn’t quite at a commensurate level of richness or sophistication.
The cabin has a good driving position, offers adult-appropriate passenger space and is appointed in a mix of quite appealing textiles and leathers – but also of cheaperlooking switches and mouldings in plenty of places. Key touchpoints, from the exterior door handles to the gear selector, feel surprisingly plasticky and lightweight, and the doors close with a tinny clang.
Isolation from wind and road noise is also a little disappointing.
And while the handling and steering are good for a larger SUV, the ride can be slightly sproingy, jittery and occasionally noisy.
Evidently Mazda still has a bit to learn about making really convincing premium cars. But in one respect in particular – a 3.3-litre straight-six diesel engine that feels ideal for towing and long-distance driving and can return 50mpg easily and 65mpg if you try a bit – it now has a selling point that plenty of us, especially those who don’t pay benefit-in-kind tax and who aren’t in a position to regularly charge an electrified alternative, could surely find a use for.