Given the poor condition of wood and iron recovered from sunken 300-400 year old Spanish wrecks near Florida, what would the condition be of wooden chariot parts submerged for thousands of years in warm relatively shallow water?Maybe so, but it seems to me that the Egyptians of this time period used mainly Bronze. The Hittites had iron, and that made them nasty folks to fight with....
I'm not an Egyptologist or student of military antiquities but my guess is the Egyptian chariots were largely composed of wood due to it's weight. Fasteners and decorations may have been metallic but I suspect the axle, wheels, floor and apron were largely wooden.
At growth rates of 1/2 inch per year, corals would have long ago overgrown their original seed material (metal chariot parts) and would now be large coral reefs. To have a recognizeable chariot part, recovered now, it would have needed to have been buried at or shortly after the Egyptian army was destroyed.