Fuel composition comprising a nitrogen-containing compound

A fuel additive concentrate comprising at least one aryl amine; and at least one metal-containing compound is disclosed. In an aspect, the fuel additive concentrate can be synergistic. Fuel composition comprising the fuel additive concentration and methods of combusting the fuel composition are also disclosed. Moreover, methods of enhancing research octane number, increasing fuel economy, and reducing the carbon footprint of a vehicle are also disclosed.