Exhaust gas fuel reforming has been examined as a process for upgrading biogas into hydrogen enriched gaseous fuel for use in transportation. The effect of different O-2/CH4 mole ratios and space velocities on the reformer product has been studied. In addition, 20% volume fraction of exhaust gas recirculation (EGR) has been introduced into the engine system to investigate the effect of engine-out exhaust composition on the reforming process. Our results imply that fuel reforming process efficiencies of up to 95% (based on the energy content of the reformate produced compared to the energy content of the biogas used) can be achieved at optimum biogas and engine exhaust gas ratios for the different engine conditions. Furthermore, the total carbon dioxide content is reduced by reforming biogas to form better quality fuel. (C) 2012 Elsevier Ltd. All rights reserved.