I’m confused, is that meant to be the car body itself, or the reflection view, or something else?
step #1: use the path-tracer to develop a ground truth of the scene. If the scene in the PT looks bad, then it’s your materials or meshes, not your lighting.
step 2: Check the lumen scene to see if it’s really using SWRT or HWRT. If it’s blurry and blobby, that’s SWRT and there’s a pretty hard cap on how good the reflections can be.
I suppose I don’t understand what you mean by ‘blurring’. If I had to guess, you’re seeing low-res lumen scene data because your scene is largely lit by the skylight? Hit lighting for reflections requires there to be a punctual light source (actual directional, spot, point, or rect light) for it to reflect against. Otherwise, the reflections will use the surface cache to evaluate sky lighting.