Simplify the following text for a Grade 9 native English-speaking person.
Original: While Formula One has generally been regarded as the pinnacle of open-wheeled auto racing , the high performance nature of the cars and the expense involved in the series has always meant a need for a path to reach this peak .
Simplified: Formula One is generally regarded as the top open-wheeled auto racing series . Because of the high performance and expense of the cars , a lower level racing series was needed for developing drivers and teams .