you can replace a blue Fiat emblem with the newer red one on a Fiat 100HP. The process typically involves removing the old emblem, which is usually attached with adhesive or clips, and then affixing the new red emblem in its place. Ensure the surface where the emblem will be applied is clean and free of residue to provide a strong bond for the new emblem. You might need to check the fitment of the new emblem to ensure compatibility with your specific model. It's a good idea to consult with a Fiat dealership or a professional for guidance on proper installation and to ensure that the new emblem matches the aesthetic of your vehicle.