NOVELTY - An exhaust gas-containing mixture comprising engine exhaust gas (3) and a hydrocarbon-containing fuel (A), is provided to an exhaust gas recycle reformer. Portion(s) of the exhaust gas-containing mixture is converted in the presence of a hydrocarbon-reforming catalyst composition comprising 0.25 wt.% or more hydrocarbon-reforming catalyst and 10 wt.% or more small pore molecular sieve under reforming conditions, to form a reformed gaseous mixture comprising hydrogen, carbon monoxide, carbon dioxide, water and/or nitrogen, and more than 1 mol% methane.    USE - Method for increasing octane rating of internal combustion engine exhaust gas stream (claimed).    ADVANTAGE - The method increases octane rating of internal combustion engine exhaust gas stream using catalyst composition with enhanced activity for methanation thereby reducing or minimizing additional heat required for reforming process.    DETAILED DESCRIPTION - An exhaust gas-containing mixture comprising engine exhaust gas having an initial octane rating and a hydrocarbon-containing fuel (A), is provided to an exhaust gas recycle reformer. Portion(s) of the exhaust gas-containing mixture is converted in the presence of a hydrocarbon-reforming catalyst composition comprising 0.25 wt.% or more hydrocarbon-reforming catalyst chosen from cobalt, ruthenium, platinum, palladium, nickel, iridium, rhodium, zinc and rhenium, and 10 wt.% or more small pore molecular sieve under reforming conditions, to form a reformed gaseous mixture comprising hydrogen, carbon monoxide, carbon dioxide, water and/or nitrogen, and more than 1 mol% methane with respect to total moles of gas in the reformed gaseous mixture. INDEPENDENT CLAIMS are included for the following:    (1) hydrocarbon-reforming catalyst composition comprising 0.25-10 wt.% rhodium, 10-99.5 wt.% CHA framework-type molecular sieve, and 0.25-10 wt.% molecular sieves (B) having a largest ring size of a 10-membered ring; and    (2) reformer, which comprises catalyst composition to convert a mixture comprising internal combustion engine exhaust gas and hydrocarbon-containing fuel to a gaseous mixture comprising hydrogen, carbon monoxide, carbon dioxide, water, nitrogen and more than 1 mol% methane.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the power train.    Compressor (1)    Turbine (2)    Exhaust gases (3)    Cooler (4)    Converter (7)