The following is found in the Singapore's National Climate Change Strategy (NCCS) report by the Ministry of the Environment and Water Resources.

The environmental merits of public transportation can be seen from a comparison of the relative energy use by the different modes of transport. It is estimated that to transport one person, a car carrying only one driver uses 9 times the amount of energy used by a bus, and 12 times the energy used by
an MRT train.

Its amazes and dismays me how such a long statement (by a govt org!) can contain absolutely no useful information at all.