The cheap gasolin is heavily subsidised by the government, but they only want to support their own citizens.
Its so cheap that Singapore has restrictions on how much gas you (at least Sing citizens) must have in the tank (3/4 full), when leaving Singapore, and they measure it at the border.
In 2008 malyasia banned all sale of fuel to foreigners,within a distance of 50km from their borders
In 2009 cars with foreign plates will only be able to refuel a maximum of 20 liters of fuel within a 50km radius from Malaysia’s borders
May you enjoy peace and good health !