What is the main purpose of a commercial driver maintaining a logbook?

The main purpose of a commercial driver maintaining a logbook is to monitor driving hours and ensure compliance with regulations. Logbooks are essential for documenting the amount of time a driver spends behind the wheel, including rest periods, to adhere to federal and state regulations regarding hours of service (HOS). These regulations are designed to prevent fatigue-related accidents by ensuring that drivers do not exceed the maximum allowable driving hours.

By accurately recording their driving hours, drivers can demonstrate that they are operating within the legally mandated limits, thereby promoting safety on the roads. Furthermore, maintaining a logbook helps in the event of an audit or a roadside inspection, as it provides official documentation of compliance with safety regulations.

The other options, while related to commercial driving, do not capture the primary purpose of a logbook. Tracking mileage for maintenance, calculating fuel efficiency, and recording maintenance costs are important aspects of vehicle management but do not pertain directly to the legal and safety requirements associated with driving hours and breaks.