2017 Mazda Vision Coupe concept
Just this month, Mazda announced they were developing not one but two inline six-cylinder engines. This news comes after decades of V6 dominance over the inline six (except over at BMW), and in turn the subsequent rise of the turbocharged inline four-cylinder over V6s in everything from German sports sedans to American crossovers. Fans of the inline six layout, widely praised for its inherent balance and smoothness, can rejoice as Mazda isn’t the only automaker to embrace the I6.
Put in context, Mazda’s new inline sixes make sense. Mazda has been slowly creeping upmarket, chasing fatter profit margins that will help insulate the relatively small automaker. Last fiscal year, Mazda’s operating profit fell 43% due to falling sales in China and increased investment in the U.S. dealership network and incentives.
Rather than reattempt a luxury marque like their aborted Amati brand in the early 1990s, Mazda is classing up their regular passenger cars while introducing larger models on a new platform architecture that will use the two engines. One of the two Mazda sixes will be a diesel, dubbed Skyactiv-D, and both are designed to work with the company’s all-wheel-drive system. The new large Mazdas will also be available with a 48-volt mild-hybrid setup and a plug-in hybrid variant.
The gasoline-powered Skyactiv-X inline six will use Mazda’s new spark-controlled compression ignition system, which will first appear on select four-cylinder models and which promises the efficiency of a diesel. For a company Mazda’s size to invest in two new engines and a new platform architecture is surprising but here’s hoping they’re able to get some solid returns on their investment.
Mercedes-AMG GT 53 4-Door Coupe
You can spin a V6 engine off of a V8 engine, albeit not without some technical hurdles. However, with V8s slowly disappearing – they’re supposedly dying, but we heard that back in the ’80s – there’s less of an incentive to develop a V6. Instead, Mercedes and other automakers can spin an I6 off of an I4.
Mercedes-Benz introduced the M256 inline six in 2017 and manufactures it in on the same production line as their four-cylinder engines. The M256 uses the same bore and similar stroke to the four-cylinder engines and is part of a modular engine family that also comprises Mercedes’ inline four- and six-cylinder diesels. To fit this inherently longer engine under the hoods of their vehicles, the 3.0 inline six uses a 48-volt integrated starter/alternator (dubbed ISG) which powers the water pump and A/C compressor, negating the need for belts at the front of the engine bay.
The M256 replaces Mercedes’ V6 engines, returning the Stuttgart brand to the inline six format after an interregnum of almost 20 years. It first appeared under the hood of European S450 models in 2017 and has since proliferated throughout the Mercedes line-up – you can find it in the GLE, CLS and E-Class ranges (with 450 or 53 AMG badging) and in the Mercedes-AMG GT43 and GT53. AMG models also employ an electrically-driven supercharger. There are two different tunes of the M256 – one producing 362 hp and 369 ft-lbs, the other 429 hp and 384 ft-lbs.
A lot of digital ink has been spilled regarding the M256 engine but there’s another inline six in Mercedes’ modular engine family. The OM656 engine, a 2.9 diesel I6, was also launched in 2017 in the S-Class and has since been introduced to the G, E and CLS lines. There are two tunes: one with 282 hp and 443 ft-lbs (in 350 d-badged Benzes) and one with 335 hp and 516 ft-lbs (400 d models). Unfortunately for North Americans, there don’t appear to be any more plans to bring this impressive engine over to the continent.
Like Mercedes, Jaguar Land Rover also has a new modular engine family. Dubbed Ingenium, this engine family comprises inline four and now inline six-cylinder engines. JLR’s “mild hybrid” inline six debuted this year in the Range Rover Sport and, on paper, it looks somewhat similar to the AMG version of Mercedes’ M256. It also displaces three liters, it’s also turbocharged, and there’s a 48-volt electrical system which powers, among other things, an electric supercharger.
The Ingenium six replaces the old supercharged 3.0 V6 and will also appear under the hood of the flagship Range Rover and likely other JLR models. Like Mercedes, Jaguar abandoned the inline six in the late 1990s in favour of V6s. The Ingenium six is available in two states of tune: one with 355 hp and 365 ft-lbs, the other with 395 hp and 406 ft-lbs.
BMW 840d
Unlike Mercedes and Jaguar, BMW never abandoned the inline six. Though its latest UKL platform models eschew an I6 in favor of turbocharged inline fours, BMW makes an I6 available in every other model line. Even the flagship 8-Series can be had with an inline six diesel in some markets.
BMW’s embrace of the inline six has actually spilled over to other automakers. The new Toyota Supra was co-developed with the latest BMW Z4 and they use the same engines – a 2.0 turbocharged inline four and a 3.0 turbocharged inline six, the latter producing 335 hp and 369 ft-lbs.
Not all inline sixes reside under the hoods of sports cars and luxury vehicles. Due to arrive for the 2020 model year in the Chevrolet Silverado and GMC Sierra, the new Duramax 3.0 six-cylinder diesel will produce 277 hp and 460 ft-lbs and be mated exclusively to a 10-speed automatic. GM truck buyers will shell out around $2500 more for the diesel compared to the regular 5.3 gasoline V8.
Though nothing has been confirmed as yet, FCA is allegedly developing an inline six engine dubbed Tornado that may see duty in Ram trucks, among other products. FCA has long offered the I6 Cummins diesel in Ram trucks but discontinued its last gasoline I6, the venerable PowerTech (nèe AMC) 4.0, over a decade ago.
The inline six’s newfound popularity is, for now, confined to rear-wheel-drive and/or all-wheel-drive and predominantly luxury brand vehicles. Though six-cylinder engines have largely disappeared from some segments, such as the mid-size segment, there are still plenty of cars and trucks using V6s. With automakers seeking efficiencies and employing modular platform architecture and engine families, will we see more and more I6s?
Related Reading:
“Mazda aims for upscale appeal with inline-6 engines” – Hans Greimel, Automotive News
Once again, CC (and in particular William) helps my knowledge of current events as well as more vintage vehicles. Thanks! Upon first reading this, I was prepping a curmudgeonly response that these sixes are all about tradition and sentiment; with modern technology, the straight six’s inherent smoothness shouldn’t outweigh its packaging inefficiency, manufacturing costs inherent in long crankshafts and exhaust manifolds etc. But in fact, I don’t know if it’s really that inefficient. With all the other stuff making up a powertrain these days, such as superchargers, Hybrid units, DEF injection, etc, perhaps a long skinny engine works out well to make room for the ancilllary stuff. I will say the Mazda is flat-out gorgeous.
perhaps a long skinny engine works out well to make room for the ancilllary stuff
This was my thought as well. Obviously, you can package a supercharger or similar ancillaries in the vee of a V-6 or V-8, but it imposes some pretty significant space limitations, to say nothing of heat dissipation issues.
So many cars and SUV/CUV are based on transverse-engine architecture. With the exception of Volvo, I can’t think of any transverse I-6 cars.
As a truck engine? Absolutely. I could see GM doing a straight-six “stretch” on the new turbocharged I-4, as an engine that might finally kill the V-8. If done right, it would be about the same displacement as the Ford EcoBoost 3.5 and probably be more powerful with more torque.
I thought about the transverse aspect. But Jaguar, BMW and Mercedes make little use of that architecture, certainly not in the larger platforms where a six makes sense. Coupled with the ubiquity of AWD variants of these cars, the north-south mounting with the in-line works well.
Austin/Morris (aka BMC) used a transverse i6 in the 1970s. It was a 2.2 litre version of the E-series i4, featuring a relatively small bore and long stroke, to make it fit the space. There was a larger capacity version used in Australia.
The Daewoo Verona, sold as the Suzuki Verona in the US, had an inline transverse six.
Wasn’t it developed with assistance from Porsche ?
I seem to recall that GM did try a modular family approach to I4/I5/I6 engines around 2001 or so…. the Atlas line.
Makes lots of sense, as the V8 really is going to become increasingly sparse, except in US trucks. It’s no different than what Chevy did back in 1962 with its four and six, and many others have since. It makes production very efficient.
About three weeks ago I was talking to a Ford salesman. His claim was Ford was scaling back on the 5.0 in half-tons as the take rate on the Ecoboost engines, particularly the 2.7, was so predominant.
A quick search of a nearby Ford dealer has 63 out of 224 equipped with a V8. 151 have an Ecoboost and only three have the 3.0 diesel.
Whether any of this is indicative of anything specific is hard to say, particularly if regional influences are a consideration, but his assessment does match what I’m finding.
In the lighter trucks, no doubt that’s the future. I was thinking of the HD trucks, specifically about Ford’s brand new 7.3 L gas V8. It’s the first all new gas V8 in the US in quite some time. I’ve been meaning to do a post on it for a while now. It’s quite an impressive motor and is compact enough to be swapped into older cars and trucks, although it’s going to require a new shallower oil pan for that.
It’s also Ford’s 1st pushrod V8 (besides the PowerStroke diesel of course) since the “old” 5.0 went away in 2001 after being last offered in the Explorer. The PowerStroke never went away & for several years was your only pushrod option anywhere in the Ford lineup (the Essex V6 family eked out its final moments in the 2008 F-150 but was still made as an industrial engine under the name ESG-642 until 2015).
I suppose it’s realistic that the gasoline engine will be around at some level for decades and that therefore technical development is still necessary. But I would have thought the need to invest in electric technology would have been the priority for most individual automakers at this point. This video on ‘barriers to EV adoption’ from last year still seems on track to me.
So ideally everyone would have a driveway to park their electric car, and a dedicated charging point installed on the wall of their home. Never going to be possible.
Saw a warning this week that some folk who do have a driveway are joining multiple extension leads together to charge their electric car from a domestic socket – sometimes in the rain….
Home charging may not even be a necessity in the future. There are already 150kW chargers that can give up to 200 miles of range in 30 minutes. And there was recent news of a Swiss startup claiming the ability to give 250 miles of range in under 5 minutes of charging time.
https://www.evo.co.uk/news/22633/new-piech-mark-zero-80-charge-in-under-5-minutes
In any case the technology is advancing very quickly. The video may be optimistic in some areas, but the general shape of the argument is valid I think.
Does that 5-minute charger use cables the size of your leg, or just use water cooling to dissipate all the energy thrown away as waste heat?
There is no miracle of room temperature superconductivity waiting in the wings. Fast charging will always be expensive, wasteful, or both.
I found a good assessment of the Mercedes inline six here:
https://youtu.be/7PkX-NH6bE0
He mentions a few things such as the manufacturing economies of fewer heads and camshafts vs a V engine, as well as better separation of exhaust and intake to help catalytic converter packaging and thermal efficiency. In addition, the design and manufacturing benefits of an inline four and six engine family, since having an available four is pretty much a necessity nowadays.
Good, I like inline sixes and diesels in particular, we get the odd Mazda 6 diesel here ex JDM and I actually considered one a straight six diesel could easily fit where ever I live.
Thats probably the most stunning car Ive ever seen.
“For a company Mazda’s size to invest in two new engines and a new platform architecture is surprising but here’s hoping they’re able to get some solid returns on their investment.”
Question from left field: Any chance they hope the new technology will be successful and they can license it to other automakers?
The Slant Six was an inline 6, maybe Chrysler can make lightning strike again.
As for Mazda, I think their days are numbered, but I hope not.
Ahem, it already did strike again!
Everything old is new again. I knew my Mercury Zephyr would lead the way to the future…
future…
future…
That’s an echo. Didn’t know how to type an echo sound.
If time/space is a circle, could you look far enough ahead to see your own butt?
If you start to travel faster than light, do you get blinded by your own headlights?
Got a little off topic there, sorry. Been watching far-out YouTube videos.
My all time favorite inline 6, the Honda CBX (on the right for non-bikers). Photo is some forgotten roadside break in Montana on leave touring in 1981.
Guys my age have memories of the dog-slow full size Ford or Chevy 6s popular in rural Wisconsin. Even lower on the kid totem pole was a Rambler.
Back then I never suspected a 6 could be made to feel and sound like an F16 on full after burner. The CBX revised my thinking. What a rush that bike was. I was always looking for reasons to wind the engine to redline – not that I needed much reason. The sound and feel were so intoxicating.
Lucky I didn’t kill myself with my rather informal hot weather riding attire.