A system of coupled locomotives comprising: (a) a first vehicle comprising: a first engine configured to combust heavy fuel; a first generator linked to the first engine and configured to convert mechanical energy provided by the first engine into electrical energy; a first coupler; a plurality of first wheels; a plurality of first electric motors configured to drive the plurality of first wheels; and a first power bus configured to electrically connect the first generator, the plurality of first electric motors, and the first coupler; and (b) a second vehicle comprising: a genset including: (i) a second engine configured to combust light fuel; (ii) a second generator linked to the second engine and configured to convert mechanical energy provided by the second engine into electrical energy; one or more light fuel storage containers; one or more electrical storage devices; a plurality of second wheels; a plurality of second electric motors configured to drive the plurality of second wheels; a second coupler; and a second power bus configured to electrically connect the second generator of the genset, the one or more electrical storage devices, the plurality of second electric motors, and the second coupler; wherein the one or more electrical storage devices are disposed lower than the one or more light fuel storage containers with respect to a vertically extending reference axis that is perpendicular to reference plane parallel with ground; wherein the first coupler is connected to the second coupler, thus electrically connecting the first power bus with the second power bus. (a) a first vehicle comprising: a first engine configured to combust heavy fuel; a first generator linked to the first engine and configured to convert mechanical energy provided by the first engine into electrical energy; a first coupler; a plurality of first wheels; a plurality of first electric motors configured to drive the plurality of first wheels; and a first power bus configured to electrically connect the first generator, the plurality of first electric motors, and the first coupler; and a first engine configured to combust heavy fuel; a first generator linked to the first engine and configured to convert mechanical energy provided by the first engine into electrical energy; a first coupler; a plurality of first wheels; a plurality of first electric motors configured to drive the plurality of first wheels; and a first power bus configured to electrically connect the first generator, the plurality of first electric motors, and the first coupler; and (b) a second vehicle comprising: a genset including: (i) a second engine configured to combust light fuel; (ii) a second generator linked to the second engine and configured to convert mechanical energy provided by the second engine into electrical energy; one or more light fuel storage containers; one or more electrical storage devices; a plurality of second wheels; a plurality of second electric motors configured to drive the plurality of second wheels; a second coupler; and a second power bus configured to electrically connect the second generator of the genset, the one or more electrical storage devices, the plurality of second electric motors, and the second coupler; wherein the one or more electrical storage devices are disposed lower than the one or more light fuel storage containers with respect to a vertically extending reference axis that is perpendicular to reference plane parallel with ground; wherein the first coupler is connected to the second coupler, thus electrically connecting the first power bus with the second power bus. a genset including: (i) a second engine configured to combust light fuel; (ii) a second generator linked to the second engine and configured to convert mechanical energy provided by the second engine into electrical energy; one or more light fuel storage containers; one or more electrical storage devices; a plurality of second wheels; a plurality of second electric motors configured to drive the plurality of second wheels; a second coupler; and a second power bus configured to electrically connect the second generator of the genset, the one or more electrical storage devices, the plurality of second electric motors, and the second coupler; wherein the one or more electrical storage devices are disposed lower than the one or more light fuel storage containers with respect to a vertically extending reference axis that is perpendicular to reference plane parallel with ground; wherein the first coupler is connected to the second coupler, thus electrically connecting the first power bus with the second power bus.