A humming or whining gearbox noise at highway speed often points to CVT fluid, bearings, or final-drive wear.
Here’s what to check first and when to stop driving.
Why a Subaru Impreza V hums or whines at highway speed
If your Impreza V starts humming or whining from the gearbox area once you're at highway speed, you're right to pay attention. In my shop, the first step is always to separate a true transmission noise from a wheel bearing, tire, or CV joint noise. A gearbox whine usually follows road speed rather than engine RPM, may change when you lift off or accelerate, and can be louder in one gear or during CVT ratio changes. On a fifth-gen Impreza, that often means the Lineartronic CVT, the final-drive gears, or a bearing inside the transaxle is talking to you.
