It depends on each engineer’s likings and abilit. Mechanical engineering covers far wider areas and automobile engineering covers more concentrated area. If the engineer likes automobile and very detailed technologies, he should take automobile engineering. If he is just like Jack of All knowledge Nd wants to experience as wide as engineering fields, he should take mechanical engineering. But after starting a job, everyday both engineers try to identify every necessary field, they should learn it himself and should be able to self learn. Now everything is obtainable through Internet.