Catalyst compositions suitable for use in the exhaust gas recycle stream of an internal combustion engine are provided. Such catalyst compositions typically provide significant amounts of methane in addition to syngas. A reformer incorporating such a catalyst for use in an exhaust gas recycle portion of an internal combustion engine powertrain is described. A powertrain incorporating such a reformer, a method of increasing the octane rating of an exhaust gas recycle stream, and a method of operating an internal combustion engine using methane-assisted combustion are also described.