This 'donut' electric motor is mounted in the wheels

It weighs 40 kg and develops up to 845 PS. Produced by Donut Lab, it avoids drive shafts and other mechanical parts

Photo by: Donut Lab

By: Francesco Barontini

Jan 9, 2025 at 5:03am ET

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Electric motors integrated in the wheels have been studied for a long time. However, the solution has never caught on because it adds weight in a place (the wheel) where lightness is a must. But now things could change. At this year's CES in Las Vegas, Finland's Donut Lab presented a revolutionary electric motor in the shape of a doughnut.

Much improved over the first version, it is more compact and lighter, promises great torque and power and, not to be underestimated, costs about half as much as its predecessor thanks to the fact that it uses about 120 fewer components.

With the hole, the weight stops at 40 kg

Placing an engine directly in the wheels offers several advantages. First of all, it eliminates the need for drive shafts, further saving weight. In addition, it allows very precise control of the driving force transmitted to the ground, due to the direct motor-wheel connection.

Furthermore, with Donut Lab's new motor weighing 40 kg, the increase in unsprung mass is negligible. However, it should be remembered that an electric car should have at least two units, if not four, to take advantage of all-wheel drive.

Gallery: Donut Lab ring motor (2025)

Source: Donut Lab

Up to 3,380 PS

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Coming to the numbers, the donut motor presented at CES 2025 is large enough to fit inside a 21-inch rim. In its most powerful version, it can develop 845 PS of power and 4,300 Nm of torque. Doing the maths, on an all-wheel-drive car, you could theoretically unload a whopping 3,380 PS and 17,200 Nm to the ground.

Dimensions: 21-inch diameter
Weight: 40 kg
Max. power: 845 PS
Max. torque: 4,300 Nm

Donut Lab is also developing other versions of this engine for other 100% electric vehicles and beyond. For example, it showed a 272 PS motor with 3,000 Nm of torque dedicated to commercial vehicles. But they are also working on a smaller 22 PS motor that can fit into a 12-inch wheel, which could be used by battery-powered scooters. They are also thinking about a 120 mm diameter 4 PS motor to be fitted in drones.