Unleaded fuel is a type of gasoline that does not contain lead additives, which were once used to improve engine performance. The removal of lead from fuel has significantly reduced air pollution and health risks associated with lead exposure. Unleaded fuel is now the standard for most vehicles, including cars and trucks. There are different octane ratings for unleaded fuel, such as Regular, Mid-Grade, and Premium. These ratings indicate the fuel's ability to resist knocking during combustion. Using the appropriate octane level for a vehicle can enhance performance and efficiency, ensuring optimal operation of the engine.