Complex sentence: The elevation of the Isle of Man was challenging for the cars; the course rose from being barely above sea-level at Douglas to at Brandywell, while many parts of the course were nothing more than rough tracks.
Split into simpler sentences: The elevation of the Isle of Man was challenging for the cars; the course rose from being barely above sea-level at Douglas to at Brandywell. Many parts of the course were nothing more than rough tracks.