https://airshaper.com/videos/motorcycle-aerodynamics/qrH_QBOrqbw

Unfortunately, open wheels, sharp edges, exposed components and a constantly moving rider cause all sorts of disturbances to the airflow. This makes it extremely difficult for air to remain attached and so the flow separates, creating wakes and generating drag. Consequently, the drag coefficient of a motorbike can range from 0.5-1.0 which is double that of a modern car.

The best cars are around 0.2. EVs have been getting close to that because they get hit hard on highway range if they don’t. ICE cars tend to be closer to 0.3.