An individual train journey (or a bus journey, for that matter) may well be more energy efficient than the same journey by car. IF there are enough people on that train (or bus) so that their individual shares of the total energy consumption is lower than that of a car. AND IF the train routing is reasonably direct so that the passengers aren't having to travel twice as many miles zig-zagging across the country to get to their destination. AND IF each passengers onward journey from the station to their final destination is neither too long nor taken using an energy inefficient method of transport, such as poorly used bus service or a taxi.
BUT, since buses and trains need a whole infrastructure to support them and have to run to timetables, you also have to factor in the energy usage of all of the services which run with few or no passengers, the energy useage of buses and trains returning to depots and workshops when not in service, as well as things like the transmission losses in the power lines on electrified tracks (which happens 24 hours a day, whether trains are running or not), the energy used by staff getting to work to man stations and drive trains, and the energy used to keep stations lit and heated.
When you factor all of these in, then the private motor car - which only consumes energy when it's doing something useful - doesn't look quite such the bad guy.