Infiniti has said it will offer a hybrid or all-electric powertrain on every model by 2021, but has been short on other details. Now, the Nissan luxury brand has revealed that hybrids will make up the bulk of its electrified lineup, but with a powertrain design that relies more on electric than gasoline power.

Future Infiniti hybrids will not have transmissions, and their gasoline engines will be used only as generators. Rather than powering the wheels directly, they will produce electricity for a pair of electric motors — one for each axle, enabling all-wheel drive. As with all other current hybrids, a battery pack will store enough electricity for all-electric running. Infiniti did not discuss a plug-in hybrid version of this powertrain, so the gasoline engine will be the only way to charge the battery pack.

The powertrain is based on Infiniti parent Nissan’s e-Power system, which is already used in small cars for the Japanese market. It’s what is known in the industry as a “series hybrid” setup, as opposed to “parallel hybrid” configurations that use an internal-combustion engine to directly power the wheels. A series hybrid offers one major advantage when it comes to fuel efficiency: the engine can operate at a more steady speed, rather than having to dramatically increase or decrease rpm to match wheel speed. That should increase gas mileage.

Yet series hybrid systems aren’t very common. The BMW i3 REx and Karma Revero are the only two currently on sale, and they’re low-volume luxury models. The Chevrolet Volt was supposed to be a series hybrid, but Chevy ended up adding a parallel hybrid mode that allowed the engine to directly drive the wheels in certain situations. Honda’s current hybrid system also comes close, but still couples the engine to the wheels sometimes.

It’s also worth pointing out that Infiniti doesn’t plan to use the word “hybrid.” Its press materials use the confusing phrase “gas-generated EV” instead. Infiniti tested “hybrid” with American car buyers and it came across as negatively perceived, Eric Rigaux, Infiniti global general manager for product strategy and planning, said in an interview with Green Car Reports. But Infiniti runs the risk of confusing potential customers, as General Motors did with its bungled advertising for the Chevy Volt.

Whatever they end up being called, the Infiniti hybrid models will launch beginning in 2021, according to Green Car Reports. The website reports that Infiniti will launch production versions of three recent concept cars — the Q Inspiration sedan, QX Inspiration SUV, and Qs Inspiration fastback. Infiniti previously said its first all-electric production model will arrive in 2021 as well.