The present invention provides a multipurpose overbased metal salt of the reaction product of a hydrocarbyl substituted amine with an itaconate, such as an N-substituted 4-carboxypyrrolidin-2-one, and methods of employing the same in lubricating compositions. Overbasing the N-substituted 4-carboxypyrrolidin-2-one can provide improved friction modifying performance to the compound as well as impart multi-functionality to the compound, i.e., the compound may function as a friction modifier as well as, for example, a detergent, anti-wear or extreme pressure agent and dispersant in lubricating compositions. The lubricating compositions containing the overbased N-substituted 4-carboxypyrrolidin-2-one are preferably intended to be employed in a method for lubricating a mechanical device, such as an automatic or manual transmission. However, it is envisioned that the compound can be employed in engine oil lubricants and any other type of functional fluid.