Disclosed herein are a display apparatus for vehicles and a method of controlling the same. The display apparatus for vehicles includes a projection glass having a variable transmittance, a variable glass driving unit configured to adjust the transmittance of the projection glass, a projector configured to display an image on the projection glass, an image input unit configured to receive an image to be projected onto the projection glass, a mode selection unit configured to select an operation mode of the projection glass, and a control unit configured, according to the selection of the mode selection unit, to drive the variable glass driving unit to adjust the transmittance of the projection glass and to project the image, input from the image input unit, onto the projection glass through the projector.