Mercedes-AMG, Mercedes-Benz’s performance arm, is joining other German automakers and embracing electric turbocharging technology. E-turbos, as they’re sometimes called, do the same work as normal turbochargers—so, acting as a compressor and forcing a greater density of air into the combustion chamber—but instead of being driven solely by an engine’s exhaust gases, they’re aided in spinning up by an electric motor.
The key advantage of e-turbos is boost that comes on right now, rather than purely exhaust-driven turbos which require time to spool up and provide boost—the dreaded turbo lag. Using a slim, 1.6-inch-thick electric motor integrated with the turbocharger’s compressor-wheel shaft, AMG’s e-turbo design (developed in conjunction with Garrett) enables the turbo to be spun up before exhaust gases are flowing, massively improving low-speed engine response and power.
E-turbos enable finer control over boost pressure generally, too, since the turbocharger’s operation is partially independent from exhaust pressure, at least at low speeds. Mercedes-AMG says that its new e-turbo will even keep the compressor wheel spinning when the driver lifts their foot off the throttle—so as to prevent boost pressure from bleeding off and deliver immediate engine response when the driver gets back into the gas. This system, by the way, is powered by a 48-volt electrical system like that in a rash of new luxury products and mild-hybrid vehicles.
Mercedes isn’t saying what product will get the new e-turbo first, or when—but it has revealed which engine will get the tech: The M139 four-cylinder, which is currently used in the new compact Mercedes-AMG CLA45 and the upcoming GLA45. That said, both of those vehicles were introduced with 382-hp versions of the M139 late last year (with a 416-hp version promised for hotter “S” models). So, unless AMG is hiding the e-turbo detail from the current M139’s spec sheet, and it’s responsible for the 416-hp iteration, the tech is likely headed for later versions of the 45-badged compact AMGs. Indeed, AMG says the e-turbo is headed for its “next vehicle generation.” We likely will have to wait for those compact AMGs’ mid-cycle refreshes or redesigns in a couple of years, then, to see e-turbo and 48-volt systems enter production.
Surely, of course, e-turbo tech would later spread to AMG’s six- and eight-cylinder models, too, especially given how the emerging 43- and 53-badged six-cylinder AMG products have 48-volt electrical systems and mild-hybrid tech onboard. Either way, Audi’s work on e-turbos soon will be challenged in the luxury-tech cage fight by Mercedes, and never before have we looked so forward to a bunch of blown hot air.
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