Complex sentence: The manufacturers involved agreed to a voluntary recall, though this did not go smoothly, with only 18% of the 8.9 million cars and trucks with the Takata belt buckle having been repaired two years after the recall had begun.
Split into simpler sentences: The manufacturers involved agreed to a voluntary recall, though this did not go smoothly. Only 18% of the 8.9 million cars and trucks with the Takata belt buckle were repaired two years after the recall had begun.