Flat greys are the hardest colour to make look expensive, because there isn't any metallic flake doing the work for you. This 2022 X3 M40i wears Icon Rocklear, our permanent paint protection coating, and you'll see the difference in how cleanly the hex lights bend across the hood and down the flank. The panels read glassy rather than chalky, which is what this shade's supposed to do and rarely does once a car's got a few years on it.

An X3's also a lot of surface to get right. It's tall, the doors and rear quarters are broad and close to flat, and the wheel arches are squared rather than rounded, so light hits them as hard edges instead of soft transitions. On a shape like this an uneven finish turns up as banding across the door skins. The side panel and rear fender frames are the ones that prove it out, along with the wheel and arch details where the reflection's got to turn a corner.

This one's a daily driven M Performance SUV, which is the use case that punishes paint hardest: commute miles, parking lots, and a lot of time sitting outside. Icon Rocklear becomes part of the clear coat instead of sitting on it as a sacrificial layer, so it resists the UV fade and the dulling behind it, and it keeps dirt and grime from getting embedded and crusted into the paint. It doesn't yellow and it needs no waxing or annual inspection.

Twenty four photos: front three quarter, straight on front, rear three quarter, then the grille and roundel, the headlight and bumper, the mirror cap, the taillight, the wheels and arches, and the side panel gloss. Grey's the colour that benefits most from this, and here's why.