New six-cylinder engines, rear-wheel drive help reformulate Mazda’s premium range
IT SEEMS like only a few short years ago that Mazda – and just about every other vehicle manufacturer – was spruiking the virtues of ‘rightsized’ engines and front-wheel drive platforms but now, all that is old is new again with a rekindled interest in straight-sixes and rear-wheel drive.
More compact, more efficient, and often more powerful than the six- and eight-cylinder engines they replaced, it seemed modern hi-tech designs with four or fewer cylinders would become the default choice until internal combustion was superseded for good.
Instead, Mercedes-Benz, JLR, Stellantis and now Mazda are joining straight-six stalwart BMW in agreeing that this engine layout offers a host of benefits over vee-configuration units.
Among these are better low-end torque response and superior refinement, thanks to a more balanced firing order; and while it may not offer the packaging benefits of a V6 or four-cylinder per se, the benefits of a straight-six are increasingly seen as outweighing its flaws.
Speaking to GoAuto at the national media launch of the all-new Mazda CX-60 this week, Mazda product development division’s CX-60 program manager, Kohei Shibata, said the move to re-embrace the inline six is one that is as much about rightsizing as the four-cylinder had been in the past, but with benefits far better suited to the brand’s premium push.
“When we decided to move towards a rear-wheel drive platform, we did it without worrying about what our rivals are doing,” Mr Shibata explained through a translator.
“We wanted to make sure we had enough future capability and scalability in our platform given the move towards electrification, and in the interim, the mild hybrid system (used in the CX-60 and forthcoming CX-90) is a very good fit with the longitudinal six-cylinder engine.
“After studying the front-wheel drive engineering platform for some time, we found that although it has been efficient in the past, it is not that efficient anymore – from an engineering perspective. And the six-cylinder is able to provide more intuitive acceleration with a stress-free feeling and minimum lag.
“Also, when considering environmental measures, we found we were able to achieve better results from a longer, longitudinal layout than we were from a horizontal layout when all other parameters (vehicle size, weight, etc.) were the same.”
Mr Shibata said Mazda quickly realised that its unique strategy is “right for the era to come”, and said it was important that a blend of technologies is offered across different markets to ease the transition to full electrification.
“The (environmental) issues we face are diverse, and one solution will not solve all our issues right away. Our focus considers the well-to-wheel scenario, offering the right vehicles in the right place, at the right time; while also providing a new option for premium SUV buyers,” he said.
“We also wanted to offer the kind of great performance and stable driving dynamics premium SUV buyers expect. When you combine all those factors as a total, we found there was no better decision than to make the move to a longitudinal platform and inline six-cylinder engine combination.”
Taking lessons applied to the third iteration of the ND-series MX-5 – currently Mazda’s only other rear-wheel drive model – engineers were able to adapt its Kinetic Posture Control suspension to satisfy the desired ride and handling combination of the far larger CX-60.
Utilising a double wishbone front and multilink rear suspension arrangement typical to many high-end European marques, Mr Shibata said the engineering team was able to deliver a level of roadholding it was simply unable to match in a vehicle with its weight centred almost entirely over the front axle.
“There are certain movements in a vehicle of this size that quite simply can be better managed through this kind of suspension design – and a longitudinal platform allows us to make that kind of design. It is because of the lessons we had learnt before that we decided to pursue this design” he enthused.
Kinetic Posture Control (KPC) applies braking to the inside rear wheel when cornering at higher G forces, helping to pull the wheel down and in turn suppressing body roll. The system activates automatically as part of the stability control system and requires no driver input to engage or disengage.
Despite similarities to torque vectoring by brake – which redistributes torque to the driven wheel that can provide the most traction when cornering to help tighten the turning radius – KPC is focused on improving vehicle posture (or ‘flatness’) when negotiating turns to deliver not only better grip, but a more refined ride for vehicle occupants.
“There are benefits for drivers, passengers and (even) pets. KPC reduces the pitching motion of the vehicle, which makes the ride more comfortable for all occupants, while also delivering obvious dynamic benefits,” Mr Shibata reiterated.
Mr Shibata told GoAuto that while it might appear Mazda has moved to make its SUV range bigger and thirstier than before, the philosophy behind its shift to a larger displacement engine and rear-biased all-wheel drive platform is as much about ‘rightsizing’ as the four-cylinder once was.
“We haven’t really changed the concept of ‘rightsizing’ itself. But in order to provide the necessary level of sophistication to customers who required a higher-riding vehicle of this size, the changes we have made, in particular in moving to the 3.3-litre engine, are just as much about rightsizing (as other examples have been in the past,” he said.
“We believe this engine is the right size for the CX-60 and other models to come, and with the fuel efficiency we have been able to achieve, we think it will be for quite some time to come.
“Having said that, things are changing and moving at a very rapid rate, and there may be regulatory movements that we don’t anticipate or expect. So, it is very uncertain for us to predict what is to come.
“But when it comes to large product group models, at this point in time, we think this sophisticated internal combustion engine operates at the best possible level, and for the life of the CX-60 at least, we would like to continue to focus our efforts on improving the internal combustion engine.”
Keyword: Mazda CX-60 redefines rightsizing