The 992-generation Porsche 911 was always ready to accommodate a hybrid powertrain, but at the time of its 2018 premiere, then-chief-engineer August Achleitner wasn’t convinced it would materialize. He told this reporter as much.
“[A hybrid] is not planned now for this part of the generation; we have to wait some years [to see] if it's really necessary from a market point of view, for some regulations maybe," he said. "And of course we would not be satisfied with today's battery technology. We could offer it today, of course, [it would] run quite well, but not quite good enough for us.”
Six years later, the hybrid 911 is a reality. A combination of stricter emissions regulations and much-improved battery technology—along with the ever-pressing need to up the performance ante—led Porsche to develop a new “T-Hybrid” powertrain, which debuts with the 2025 911 Carrera GTS. It’s not like any other hybrid system out there.
There’s a crackdown on fuel enrichment at high engine loads. Modern performance engines apparently go to richer air-fuel mixtures at higher speeds to boost performance at the expense of emissions. But this will no longer fly. So Porsche developed a hybrid system that accounts for a 64-hp boost over the outgoing Carrera GTS model, but keeps the engine running at the ideal air: fuel ratio of 14.7:1 all the way up to redline. (Porsche refers to this running condition as Lambda = 1, but a lot of Americans will be familiar with the term “stoichiometric” which refers to the same thing.)
The whole thing is driven off a 1.9-kWh, 400-volt battery that sits under the front hood of the 911 in the same place as the 12-volt battery in a non-hybrid 911. It weighs just 59 pounds—not substantially more than a traditional battery of the same size. The regular 12-volt battery moves to a compartment underneath the parcel shelf behind the rear seats.
From the battery there are two main hybrid components, a traction motor mounted within the bellhousing of the eight-speed dual-clutch gearbox, and a single electric exhaust-gas turbocharger for the new 3.6-liter flat-six. The traction motor provides up to 53.6-horsepower and 110 pound-feet of torque, and helps with off-the-line response. However, the motor can’t drive the car on its own, which is a big distinction between this “T-Hybrid” system and Porsche’s plug-in “E-Hybrid” powertrain we’ve grown familiar with over the years. There’s also no way to shut off the engine and allow for 0-rpm coasting either.
The electric turbo works like a traditional exhaust-gas turbocharger, but there’s a 14.7-hp electric motor mounted on the shaft between turbine and compressor wheels. It helps spool up the turbo more quickly, significantly reducing lag, and it can also recuperate energy to send back into the battery. It’s a huge turbo, and the first single-turbo application for a 911 in 30 years.
Porsche says the engine itself is virtually all new. It’s part of the same 9A family of direct-injection boxer engines that debuted with the 997 facelift in 2008, but it’s the first to carry the designation 9A3. Compared with the 3.0-liter 9A2 engine used in the previous Carrera GTS, bore is up by 97 mm and stroke is up by 81 mm for 3.6 liters in total. The hybrid system eliminated the need for a traditional belt drive, so the air conditioning and power steering are driven electrically. This allowed Porsche to reduce the overall height of the engine by 110 mm, and now, the inverter, DC-DC converter, and intercooler sit above the engine.
The engine uses Porsche’s Variocam variable-camshaft adjustment system, and like the 4.0-liter flat-six in the 911 GT3, it uses roller finger followers instead of traditional bucket-and-shim tappets to open and close the valves. Like the 3.0-liter—which will continue in the base Carrera, and possibly future 992 variants—the rev limit is 7,500 rpm. Output of the engine on its own is 478 hp and 420 lb-ft of torque, representing a five-hp bump over the old Carrera GTS flat-six and an identical torque figure.
But when combined with the traction motor, total output is 532 hp and 449 lb-ft of torque. (If you’re wondering why the torque output here is not 420 + 110 lb-ft, it’s because the engine and motor make their peaks at different speeds.) The hybrid system means that the manual-transmission Carrera GTS is dead—though expect Porsche to keep offering stick-shifts on other 911 models—but you still have the option of rear- or all-wheel drive. Porsche wanted to continue offering rear-wheel drive as an option for this T-Hybrid system, contrasting with other performance hybrids on the market.
The new rear-drive Carrera GTS coupe weighs 103 pounds more than its predecessor for a total of 3,536 pounds. Most of the weight increase is a result of the hybrid system, though the GTS also gets more standard equipment for 2025, including rear-wheel steering and 10mm wider rear tires. Porsche also tells Motor1 the weight distribution doesn’t meaningfully change—the 315-section rears are mostly just to deal with the extra power.
With hindsight, a 911 hybrid was, perhaps, inevitable. A lot has changed since the 2018 debut of the 992. Yet, Porsche doesn’t seem to be treating this as a cynical exercise. They’re quite proud of this novel application, the power increase it brings and the relatively small weight penalty. We’ll get our own shot behind the wheel soon.
