In central locations of the region such as Kalamata, Verga, Messini, Pylos, Kyparissia, Gargaliani, etc. you will find gas stations to fill up your tank. Gas prices range from €1.52/liter (June 2015), however, these prices change regularly.
For more information of gas station addresses and prices go to www.fuelprices.gr/GetGeography.