A full exterior repaint adds weight to a car. On a road car, this doesn't matter. On a race car submitted to FIA or ACO scrutineering, it can mean failing minimum weight or missing a class limit by a rounding error.
The numbers
A factory-standard paint system on a GT car typically runs 300–450 microns total — primer, colour, clear. At roughly 1.5 g/m² per micron, a full-size sports car with ~8 m² of painted surface adds between 3.6 and 5.4 kg of paint. Against a 5 kg ballast budget, that's your entire margin.
What we do differently
For every race build, we log each panel's mass to ±2g before stripping, after stripping, after primer, and after colour. This gives us a real-time picture of the weight being added and where we have room to optimise.
For scrutineered builds, we default to 1K clear over colour rather than 2K. 1K is lighter and thinner — typically 50–60 microns versus 90–130 microns for a full 2K system. The tradeoff is chemical resistance, which doesn't matter for a race car that's detailed after every event anyway.
On some builds we go further — bare metal in non-visible areas, or a single-stage sealer in place of primer on panels that are behind aero elements.
The documentation
At handover, race builds get a mass log by panel with before and after weights, the exact coating system used, and the total added weight. Some teams need this for scrutineering; all of them need it to know what their car actually weighs at the next event.
If you're building a track car and you haven't been told what the paint weighs, ask.