I was surprised by SUVs being able to have more window tint, and I looked it up, and you’re right [1]. For windshield and drive side windows it’s the same as a sedan, but for rear windows it can be darker for passenger comfort.
Apparently in Alabama at least, the manufacturer determines the designation [2]. So you might be able to call Subaru about the Impreza and have them call it “an SUV” to get that sweet rear window tint.