The Transverse I6 Layout Was Only Ever Used By Three Automakers

Apr 03, 2025

The inline six-cylinder engine is experiencing something of a revival of late, with several automakers returning to the format in the last couple of years. Mercedes-Benz, Stellantis, Mazda, and Jaguar Land Rover all have I6s in their lineups to replace their V6s. BMW, of course, has never abandoned the I6, and it’s the only six-cylinder format the Bavarian automaker has ever used. Until 2016, Volvo still used an I6 as well, in cars like the S60 and XC70.

Volvo is a Swedish automaker owned by Geely since 2010 and headquartered in Gothenburg Sweden. Founded in 1927, it has evolved into a premium automaker renowned for its safety, famously giving away free access to the patent for the three-point seatbelt in 1959, saving countless lives since. Volvo has also continually pushed to include the best safety tech in its cars ahead of time, and set a mission in 2007 that by 2020, no one would be killed or seriously injured in a Volvo. Today, that mission has evolved to avoid all collisions in a Volvo. Volvo was also an early adopter of EV technology and had planned to go all-electric by 2030, but recently pushed back this deadline, instead aiming for a 90-100% electric or plug-in hybrid goal by 2030 instead.

But Volvo did things differently. Because the Swedish automaker already started switching to platforms that exclusively used a transverse engine layout, all the inline six-cylinder engines of all the Volvos of the last quarter of a century or so were installed transversely - a very unusual engine layout not seen anymore today. There are many advantages to using this layout, though. Here's the low down on the transvere I6.

This article recalls the rare transversely installed engine layout of years gone by. No current cars manufactured anywhere still use this layout, and you can’t buy any of the cars mentioned in this article new anymore. They are now only available on the used market. The BMC cars were never sold in the US at all.

An inline six-cylinder engine is in perfect primary and secondary balance, which means it runs exceptionally smoothly without the need for any additional balancing measures, such as balancer shafts. This excellent running refinement makes it an ideal engine for executive cars, and it’s what BMW has built its legacy on for decades. Today, the automaker’s B58 I6 is its latest generation of inline sixes, and it’s built a reputation for a very robust design that can absorb lots of boost thanks to its stout closed-deck engine block and strong bottom end. It’s even found under the hoods of other brands, such as in the Toyota GR Supra and the Ineos Grenadier.

The B58 is a surprisingly adaptable engine and can provide varying levels of power to suit many different cars and powertrain combinations.

But the I6 has turned out to be a practical choice too. It’s cheaper to build than a V6 engine, because it has a simpler block with the cylinders inline and only a single cylinder head and two camshafts, whereas a V6 requires the doubling up of these components. Another advantage is that it can easily be developed off an inline four- or five-cylinder engine by simply adding additional cylinders, enabling the engine to be built on the same production line as the smaller derivatives, saving not only production, but also development costs. With an electric water pump and ancillaries placed on the side of the engine, the space normally taken up by pulleys to drive this equipment can be deleted, shortening the engine even further.

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If it sounds like the transverse I6 is commonplace because three entire automotive groups used the layout, let’s put that into perspective. There were essentially only three basic designs of such a powertrain configuration from three automakers, and the same mechanicals were reused for different brands, so it remains a rare layout, despite various nameplates being associated with it. The first we look at is Volvo, whose modular inline six-cylinder engine first appeared in the 1990 Volvo 960.

Volvo Transverse Modular I6 and SI6 Specifications

Years Made

1990-2018

Available Sizes

2.4L, 2.5L, 2.8L, 2.9L, 3.0L, 3.2L

Aspiration

Natural or turbocharged

Horsepower

161-350 hp

Torque

160-369 lb-ft

In the ’90s Volvo 960, S90, and V90, it was installed longitudinally, driving the rear wheels. The first-generation 1999 S80 sedan was built on the Volvo P2 platform, which meant the I6 was rotated through 90 degrees and sat transversely under the hood for the first time, complete with a specially designed, extra-compact transmission to fit on the end of the engine. The original Volvo Modular I6 was used in a transversely mounted layout in the 1999-2006 S80. Under Ford and PAG, a development of this engine called the SI6 was introduced in 2006 in 3.0L and 3.2L variants, and these versions were used in a variety of Volvos, including:

The only version of the Volvo SI6 ever to be used under the hood of a vehicle other than a Volvo from the factory would be the Land Rover Freelander II, which used the 3.2L naturally aspirated SI6 for the model years 2006 to 2012, because Land Rover was also part of PAG at the time. The smaller I5 Modular Volvo engine was, of course, used in quite a few more cars, including the Ford Focus RS500 and ST, the Mondeo XR5, and the Renault Safrane.

The smooth powertrain has come a long way.

BMC, which became BL in 1968, wanted to replace it's A- and B-Series engines, and the result was the E-Series, designed from the start as a modular four-cylinder that could be expanded to six cylinders. The smallest version of the I4 was a 1.5L with 69 hp, but there was a 1.75L version too. The bore was a tight three inches, the bores were siamesed to save space,and there were no water galleries between the cylinders, all in a bid to make the engine as short as possible, because it was earmarked for transverse installation in several FWD BMC products.

Two cylinders were added to create a 2.2L I6 for the BMC ADO17 family of cars, which included the Austin 2200, the Wolseley Six, the Wolseley Saloon, and the Morris 2200 - all with the E-Series I6 installed transversely under the hood and driving the front wheels. The E-Series was a legacy of the A-Series engine in the original Mini and shared its unusual layout with the transmission underneath the engine in the sump. This - in addition to the OHC valvegear - made the engine unusually tall, requiring high hood lines to accommodate it, and leading to awkward styling of all the cars that featured it. A larger 2.6L version was also made, but it was only ever installed longitudinally, driving the rear wheels of cars such as the Rover SD1 and Austin Marina.

BMC Transverse E-Series I6 2200 Specifications

Years Made

1970-1982

Available Sizes

2.2L

Aspiration

Natural

Horsepower

110 hp

Torque

124 lb-ft

The 2.2L E-Series I6 was installed transversely under the hoods of the:

No horsing around, these ten cars with straight sixes really delivered on the horsepower front.

The current GM Korea came into being as GM Daewoo in 2002, when the Korean Daewoo Motors were split off from its parent company and became part of GM. But before that time, when Daewoo Motors was still an independent company, it developed the XK6 inline six-cylinder engine, not to be confused with the famous Jaguar XK six-cylinder engine from 1949-1992. The Daewoo I6 was a thoroughly modern engine with double overhead camshafts and four valves per cylinder. It was installed in the Daewoo Magnus mid-size sedan, which never came to the US - not with a Daewoo badge, anyway.

The Magnus was a relentlessly badge-engineered car, which was also sold as the Daewoo Evanda in countries such as Gibraltar, the Formosa Magnus in Taiwan, and the Chevrolet Evanda in Eastern Europe. It was badged as a Chevrolet Epica in Canada, and this derivative was sold in US territories such as the Northern Mariana Islands and Guam, but never in the US itself. Bizarrely, the only version of the Magnus with its transverse I6 ever to make it to the US was the badge-engineered Suzuki Verona - not any of the Chevrolet versions - sold Stateside until MY2006. We only received the 2.5L version, but there was a 2.0L I6 in other markets too.

Daewoo Transverse XK6 Specifications

Years Made

1996-2006

Available Sizes

2.0L and 2.5L

Aspiration

Natural

Horsepower

138-168 hp

Torque

135-181 lb-ft

It’s safe to say that the transverse I6 is gone for good. It’s been replaced with the ubiquitous turbocharged I4, which is cheaper to make and can produce plenty of power. The latest Volvos with the T8 PHEV 2.0L turbo-four powertrain, like the XC90 Hybrid, make up to 455 hp - more than any of Volvo’s five- or six-cylinder powertrains managed back in their heyday.

The turbocharged and supercharged engine was gone long before the new facelift, here’s why.

There is, of course, a turbocharged transverse I5 left on the market, but it’s not a Volvo. It’s the 401-hp Audi RS3. But that’s living on borrowed time as well, as the VW Group’s EA888 2.0L turbo-four is slowly replacing every transverse engine in all the automaker’s high-performance cars. When Audi’s I5 is gone, it will be the last of its kind to go, and it serves as a reminder of the days when Volvo shoved its legendary five-pot into all its cars. And that engine existed thanks to its famous Volvo I6 big brother.

Sources: Volvo, GM, FCPEuro, The Autopian.

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The inline slant transverse six can be extremely short. And it's more efficient, better, and more durable than a turbo 4.

Decisions aren't made with an eye to quality, value, longevity, or anything else except profit. Cars are deliberately made to die as quickly as possible without causing too many warranty repairs. Remember, oligarchs consider you to be nothing but food.

Planned obsolescence should be illegal, it damages the planet by making things and throwing them away unnecessarily, causes grotesque levels of pollution. If the government won't enforce it, we must, through market forces. Refuse to buy cars that wont last 400k, which has 'emissions systems' bolted on which destroy and clogg up the engine

Planned obsolescence

Governments forcing automakers to be green and get x per gallon is the problem

160k miles on my T6. Only thing that died was the fuel pressure sensor.

These new low cubic capacity turbocharged engines seemingly generate a lot of power on paper but cannot match the older engines when it comes to durability. A turbocharged inline four unit will crumble before an inline six or V6 does. Bolting on a turbo, supercharger or an electric motor is not a panacea or substitute for real precision mechanical engineering.

The Volvo 5 pot "white block" modular engine was preceded by the RWD I6 in the 960 in 1991. The transverse I6 came several years after the I5.

Bmw m1 had a inline 6 engine mounted sideways..

I had the cross-six Daewoo, which I bought new under a Japanese brand name. It had a mediocre four speed transmission, a low state of tune, and a 2.5 liter double-overhead transverse 6 engine. Despite the low power, it was a very sweet, smooth, and reliable engine--and car. Driving through mid-American freeways, we would cruise at 90 miles per hour with no sense of stress. Not much passing power either. The car dropped out of the USA market but survived another year or two in Australia under a GM name brand, but with an updated five or six speed automatic transmission. If the car had been marketed with a turbocharged engine and better transmission, from the start, it might have been a far greater success. Both Daewoo and the car have disappeared, and Daewoo was absorbed into another car company.

The "Tiny Friendly Giant" deserves a chance, and we think these cars would be perfect for it.

The problem lies with the intake valves on six Ford and Lincoln vehicles.

In need of a four-banger that can put out more than 400 lb-ft of torque? Toyota has your solution.

The Mercedes-Benz S-Class is one of the most respected luxury cars on the road, but the version with the largest engine came long ago.

Nissan's V6 engine is reliable, powerful, and durable enough to feature in a wide array of different vehicles from trucks to sports cars.

They're not all Toyota motors, either.