Minecraft wiki entry for Minecart_with_Furnace, associated text: When powered, minecarts with furnaces cover 240m per minute (about 4 m/s, slightly slower than walking speed) or 720m per piece of coal. They do not accelerate beyond this speed when going downhill or on active powered rails, and as long as they remain powered, they do not slow down when going uphill, on inactive powered rails, or when pushing or pulling other minecarts.