Monitoring the environment is an essential part of driving, as it increases the driver's situational awareness and enables them to make appropriate decisions for safe and comfortable driving. This paper presents a study to investigate how much and in which way should information be displayed to the driver in a semi-automatic vehicle with a head-up display (HUD) to achieve optimal situational awareness. This was evaluated from two perspectives: the user's experience and perceived usability. It additionally explored the users preferences on which information should be displayed in such HUDs. For this purpose, four prototypes of a visual HUD were created, displaying different amounts of information (MIN vs. MAX) and presented in two different modes - as a two-dimensional (2D) projection on the windshield and using augmented reality (AR) to highlight the information directly in the environment. The obtained results gave a clear indication that the test participants preferred to have more information displayed on a HUD, regardless of whether it was presented in 2D or AR.