Final answer:
Leaning the mixture to peak EGT is about finding the most efficient air-to-fuel ratio for fuel consumption, which is important in both aviation and automotive applications. MTBE was used in racing for this purpose but is now less common due to environmental concerns. Achieving the best economy involves both performance optimization and adherence to safety and environmental standards.
Step-by-step explanation:
For best economy, leaning the mixture to peak Exhaust Gas Temperature (EGT) refers to adjusting the air-to-fuel ratio in an engine to achieve the most efficient fuel consumption. In aviation, this is a common practice for piston-powered aircraft. The statement suggests that for optimal fuel economy, the mixture should be leaned until the EGT reaches its highest value, which indicates that the fuel is burning most efficiently. Regarding race cars, efficient fuel consumption is also critical for performance and economy. Methyl-t-butyl ether (MTBE) has been used to increase the efficiency of fuel burning, thereby providing a competitive edge. However, its use is declining due to environmental concerns, specifically the risk of groundwater contamination. Both aircraft and race car engines seek to optimize the balance between performance and fuel economy, but they must also consider safety and environmental regulations when selecting fuel additives or designing fuel systems.