What feature does the Main Display Page provide?

The Main Display Page is designed to provide essential information relevant to emissions testing, including the high and low gas percentages. This feature is crucial for inspectors as it allows them to monitor the emissions output of a vehicle accurately. By showing the range of gas percentages, the inspector can quickly identify whether the vehicle's emissions are within acceptable limits or if there are any indicators of potential issues that need further investigation.

While the other choices may represent valuable information in various contexts, they do not directly pertain to the functionality of the Main Display Page during emissions inspections. Emission testing schematics might be important for understanding the process, and vehicle history is helpful in evaluating overall vehicle performance, but the primary focus of the Main Display Page is to provide real-time data on gas emissions, making the high and low gas percentages the correct and most pertinent feature. Fuel efficiency metrics, while related to vehicle performance, do not specifically address emission levels, which is the critical aspect considered during the inspection process.