A vehicle bond filler formulation is provided that includes a part A having curable resin and a monomer reactive diluent. A part B storage-separate, cure initiator package contains a free-radical cure initiator. At least one color changing dye adapted to change color upon mixing the part A and the part B and within ±5 minutes of cure of the curable resin to a sandable condition is present in either the part A or a separate part C, a guide coat colorant, or a combination thereof. A process of for repairing a vehicle body is also provided that includes mixing a part A containing the at least one color changing dye with the part B to form an internal guide coat mixture applied to a substrate of the vehicle body in need of repair. The mixture cures causing the color changing dye to the terminal change color within ±5 minutes of cure of the curable resin to a sandable condition.