While engine downsizing is often a melancholy topic for enthusiasts, there’s one bonus in a world of inline-4-cylinder engines: It’s leading to the resurgence of the inline-6.
Engineering Explained host Jason Fenske broke down why the inline-6 is making a comeback, and it’s not really because enthusiasts adore it. In fact, it’s because the configuration saves automakers money. Recall, when the industry banked on big V-8s as their top-performing powerplants, the V-6 was often the less-powerful, more fuel-efficient stepbrother because many automakers could produce them by simply chopping two cylinders off a V-8 (though that made for a less efficient 90-degree V-6 as opposed to the more efficient 60-degree V-6). As automakers have moved to more inline-4 engines with turbochargers to boost power, it only makes sense to add two more cylinders and create inline-6s.
Thus, an automakers can often produce inline-4 and inline-6 engines on the same production line with similar tooling. That’s exactly the case at Mercedes-Benz, which Jason focuses on in the video. The new inline-6 is making its way into numerous new Mercedes vehicles, most recently into the GLE that Jason is driving in this video.
That’s not the only reason inline-6s provide an advantage for automakers. They’re far less complex than V-6s. Compared to a V-6, an inline-6 has only one cylinder head instead of two, often just one turbocharger, two camshafts rather than four, one exhaust manifold, and only one catalytic converter instead of two. As a bonus, inline-6s are also inherently smoother and better balanced, too. That makes for silky acceleration. And just listen to the 2020 Supra to understand how good the engines can sound when tuned properly.
One issue with inline-6s is fitting them into engine bays because they can be so long. The answer is opting for smaller bores and a longer stroke to create an engine the same size as a comparable V-6 while shortening its length.
Mercedes-Benz isn’t alone in re-embracing the inline-6. Land Rover revealed a new inline-6 earlier this year; Mazda confirmed plans for its own inline-6; and Fiat Chrysler has long been rumored to have its own inline-6 in the works to replace its V-6.
Jason dives into more specifics about the Mercedes-Benz engine, which has some great technology of its own, in the video above. Click play to nerd out over the return of inline-6 with us.