Model tested:Mazda 6 SKYACTIV-D prototype. Loaction: Sandown Raceway
Mazda’s technology umbrella for its next generation of cars is called SKYACTIV, only you won’t have to wait long for this cutting edge technology, as it’s coming to a Mazda showroom near you sometime later this year.
SKYACTIV is all about efficiency; efficient engines, efficient transmissions, efficient chassis and efficient car body technology.
But don’t think for one minute that efficiency by SKYACTIV equals ‘dull’ or 'boring’, because we’ve driven it at Sandown Raceway and it’s anything but dull. In fact, Zoom-Zoom is well and truly alive.
Kiyoshi Fujiwara, Mazda’s Executive Officer for Product Planning and Powertrain Development, told us after rattling off innumerable facts and figures, that the
“most important thing was to make it more fun to drive. That’s harder to measure. It’s something you feel”.
The benchmark car for SKYACTIV engine development, when it came to responsiveness to driver input, was the iconic MX-5. It’s a car that offers race car-like response rates and delivers one of the world’s best ‘behind the wheel’ experiences outside that of a supercar from Italy.
Fujiwara went on to say,
"Oneness between car and driver is our goal. That’s more important to us than absolute power. It’s that response and linearity that make driving fun.”
We couldn’t agree more, Mr Fujiwara.
Mazda’s vision is to make “cars that always excite, look inviting to drive, are fun to drive, and make you want to drive them again", but at the very same time, delivering a greener footprint on the environment. What that means for drivers is more torque, more power, greater response, and at the same time, the ability to deliver 30 percent better fuel economy by 2015 compared with 2008 consumption levels.
By employing SKYACTIV technology across all new models, Mazda believes it has cracked the code which can provide
“driving pleasure and environmental and safety performance without the slightest compromise”.
It’s a big call, but just to prove that SKYACTIV is not just a blue sky vision, Mazda shipped a Mazda6 Diesel prototype to Sandown Raceway earlier this week, loaded with a full suite of SKYACTIV technology, for some high-speed test drives by the motoring press.
Let’s just say, this is no ordinary Mazda6 Diesel. Blasting down the back straight at 150km/h-plus, it feels more like a Mazda6 MPS than any diesel variant I’ve ever driven. It doesn’t even sound like an oil burner. Once this thing hits 2000rpm and the second-stage of the turbo kicks in, things get a whole lot more urgent as peak torque is reached and stays on song all the way to 4000rpm. This is what SKYACTIV and SKYACTIV-D are all about.
In SKYACTIV-D form, Mazda engineers have broken new technological ground in creating the world’s lowest diesel-engine compression ratio of 14.0:1, which has meant a further and significant weight reduction program has been possible. There’s 25 kilograms from the use of an aluminium cylinder block alone, instead of the more traditional cast iron. Even the cylinder head is three kilos lighter, and the weight of the pistons has been reduced by 25 percent.
Lowering the diesel engine’s compression ratio is truly a breakthrough achievement, as Mazda has effectively solved the two biggest issues that have so far prevented the spread of low compression ratio diesels. The problem with reducing the compression ratio is that the compression temperature is reduced as well thus preventing complete combustion, and, the engine from starting. The low compression temperature and pressure also promotes misfiring during the warm-up stage.
Not only does SKYACTIV D technology eliminate the critical roadblocks to low compression ratio diesels, but it also does so while achieving 20 percent better fuel economy than the current diesel engine. And the story just gets better when it comes to emissions, as SKYACTIV-D is clean enough to comply with the EU Stage 6, US Tier2Bin5 and Japan’s Post New Long-Term Emission Regulations without resorting to expensive NOx treatments, which can trap these particulates and soot emissions.
By far the biggest beneficiaries of SKYACTIV technology will be Mazda drivers, when Mazda executives told the press corps that they believed that vehicles fitted with the technology would be no more expensive than current models.
The results on track with the Mazda6 2.2-litre diesel were extraordinarily good, with so much torque on tap from so low down in the rev range, that accelerating out of corners felt as though there was a larger displacement engine under the bonnet.
SKYACTIV-G is what Mazda’s next generation petrol engines are called, and just like the diesel versions, is a product of breakthrough technology. This is a highly-efficient direct injection 2.0-litre engine with an extremely high compression ratio (14.0:1), that develops 15 percent more low- and mid-range torque than the Mazda’s current 2.0-litre petrol powertrain. Not only that; remarkably, fuel consumption falls 15 percent to around the same rate the current diesel engine uses.
High compression ratio engines are not without their problems, the biggest of which is abnormal combustion or knocking. The normal compression ratio for a petrol engine is anywhere from 9:1 to 12:1. By raising the ratio to 14:1 there is a greater thermal efficiency. When knocking occurs in petrol engines, the side effect is significant drop in torque, and this factor more than any other has meant high compression ratio engines have not been developed for mass production.
SKYACTIV technology has effectively dealt with the knocking caused by high temperatures and compression by redesigning the exhaust system to create a '4-2-1' exhaust system, which effectively captures burnt gases, a design not too dissimilar to the systems used on Formula One cars.
The big surprise driving the SKYACTIV-D on the racetrack was how smooth and torquey the car was, when accelerating out of a low speed corner. That’s a product of SKYACTIV-DRIVE; the all-new six-speed automatic transmission, that’s not only quick shifting, but Mazda believes is a product of the best features of all three types of auto boxes; meaning Step Automatic, Continuously Variable (CVT) and Dual clutch (DCT).
While the unit was certainly quick to respond, I doubt the shifts were as quick as those you get when using a DSG transmission from the Volkswagen Group. That’s not a problem, as SKYACTIV-DRIVE is a more holistic approach to transmissions, so it’s a lot smoother than a DSG transmission at low speeds, where they can be rather jittery in stop/start traffic conditions. It’s also exceptionally quiet too; there’s no mechanical noises whatsoever between shifts, and let’s not forget, the car we drove was very much a prototype as you can see by all the cladding on the panel skins.
The key difference with SKYACTIV-DRIVE is that this six-speed transmission is ‘locked’ up 90 percent of the time in everyday driving conditions, whereas a traditional automatic is locked up only 50 percent of the time, causing slippage. The difference is considerable, as SKYACTIV-DRIVE offers significantly better throttle response than current Mazda6 automatic we drove back-to-back on the same circuit. The other benefit is a four to seven percent fuel efficiency gain due to the virtual elimination of slippage between shifts.
Although markets such as the United States, Japan and Australia are dominated by automatic transmissions, Europe remains very much a manual market, especially in the small to medium car segments. To cater for this position, Mazda has developed two versions of SKYACTIV-MT manual transmissions for large and mid-size cars. While we didn’t get to experience the ‘MT’ gearbox, drivers can expect a light and crisp shift feel with short shift stroke, not unlike that of an MX-5.
In order to achieve such sharp characteristics, Mazda engineers have reduced the weight of the new gearbox by 16 percent. The transmission uses a triple-shafted gear train for the ‘large’ version, which allows for a common gear for 2nd and 3rd gear ratios. This has meant a 20 percent shortening of the secondary shaft.
It’s a complex system in theory; suffice to say that the number of components and the weight of the gear train has been reduced by three kilograms.
As much work that has gone into SKYACTIV engines has also been applied to weight reduction and strength of the body and chassis, and those remarkable effects of SKYACTIV-Body and SKYACTIV-Chassis were more than evident and clearly demonstrated through the tighter sections at Sandown, where the prototype Mazda6 felt immediately lighter and considerably more agile than the current model cars.
It’s more than weight, but certainly, that’s a big part of the SKYACTIV program. It’s not that the Mazda 6 (at between 1455kg and 1597kg, roughly), is a heavy car when compared with others in the same class, it’s just that with the application of this technology, the overall weight of the prototype was around 130kg lighter when compared with the current model weight. And this is still just a prototype.
The story gets better, too. Even though the weight of the body has been reduced, rigidity is up by 30 percent through the use of more high-tensile steel in the construction process. Again, you can feel increase in stiffness on track, as the car is able to carry a lot more speed through the corners than the current model, and it does so quite effortlessly.
There are more spot welds, thinner gauge steel, but stronger framework has been applied for not only a lighter and stronger body but for an altogether safer body through multi-load paths. And there are likely to be further weight reductions under the SKYACTIV regime, as Mazda engineers are quick to point out that many car companies are using up to 60 percent high tensile steel, whereas they are using just 40 percent of the lighter gauge metal.
Big reductions have also been made with the chassis, too, with no less than a 14 percent drop in weight over the current model. The front and rear suspension systems and the electric power steering unit have all been newly developed to provide that “oneness between car and driver”. After our relatively brief albeit focused test laps, you’d have to say that Mazda has achieved its ultimate goal of a more rewarding driving experience, but at the same time providing better fuel efficiency and a greener footprint.
Mazda Australia has said that SKYACTIV technology will be seen in production cars later this year, although that will most likely be SKYACTIV engines and transmissions to begin with, while the full suite of the technology will be introduced on new models further down the track.