This invention relates to a method for forming a multi-layer coating on a vehicle body, comprised of applying primer coating, base coating, and clear coat layers in a wet-on-wet-on-wet manner, and simultaneously curing the applied three layers together in a single baking step. The primer layer comprises a film-forming binder (a) a caprolactone-modified linear acrylic polymer; and (b) an aminoplast resin crosslinking agent, wherein the composition is essentially free of crosslinked nonaqueous dispersion resin particles or crosslinked microgel resin particles or both. The resulting multi-layered coating film has excellent aesthetic appearance, strike-in resistance, chipping resistance, sag resistance, and film build even when formed in a three wet layered application method.