Complex sentence: The winning 8 hp Panhard et Levassor of Mayade had been extensively upgraded for 1896, using their first four-cylinder engine, doubling the horsepower from the 1895 model.
Split into simpler sentences: The winning 8 hp Panhard et Levassor of Mayade had been extensively upgraded for 1896. It used their first four-cylinder engine, doubling the horsepower from the 1895 model.