One part you will never see just made the new Lexus RZ noticeably quieter
Lighter, cheaper to build and effective against high-frequency whine — Sumitomo Riko’s single-material urethane eAxle cover debuts on the electric Lexus RZ.
Some parts sell a car. Others the buyer will never even notice — and those are the ones that make it quieter. The new Lexus RZ just got one. Sumitomo Riko says its high-rigidity urethane eAxle cover has landed on a production Toyota for the first time — and it debuts on the electric Lexus.
It’s the cover over the eAxle, the so-called “heart” of an EV, where the electric motor, reduction gear and power electronics live in a single unit. And here’s the EV paradox: the quieter the car gets, the more you hear what a roaring gasoline engine used to drown out. No engine hum — so whine, vibration and a thin high-frequency buzz from the drivetrain move to the foreground. That’s why the fight for silence runs not only through thick cabin insulation, but through the little things around the motor itself.
The cover is molded from “high-rigidity urethane.” Older designs stitched together plastic and urethane — two materials, two steps, extra weight. Now Sumitomo Riko promises the same noise absorption from a single material. Throw in easier mounting to the eAxle, less mass and lower CO2 emissions at the production stage.
A trifle? On paper, yes. But a premium electric crossover today doesn’t sell on range and screen size alone. It sells on the feeling of silence. For the Mercedes-Benz EQE SUV, BMW iX and Audi Q8 e-tron, acoustic comfort has long been baked into the price — and Lexus simply can’t afford to lose on the nuances that make a car feel premium.