Sorry Alan, but matching the color of old concrete is nearly impossible. The amounts of portland cement and color of the sand greatly affect the final result. If you applied a patching compound, the portland quantity would be much higher than the original concrete, resulting in a deep gray look. Obviously, many years of solar rays will tend to lighten it up some, but matching the old concrete coloring will not occur, in my opinion. My suggestion would be to mix a slurry of portland and water and apply to the entire driveway, thus resulting in a "new" look for the whole thing. Apply using a stiff bristle brush or broom. Good Luck.