Abstract: A method for displaying a warning message in a first vehicle, includes transmitting from a second vehicle a warning and position data relating to a position of the second vehicle to the first vehicle, wherein if, after reception of the warning and of the position data by the first vehicle, it is concluded on the basis of the received position data that the second vehicle can be seen by a driver of the first vehicle in a region of a head-up display of the first vehicle, the warning message is displayed in such a way that the second vehicle is characterized visually for the driver of the first vehicle in the head-up display of the first vehicle.

Abstract: In a method for checking the plausibility of objects in driver assistance systems for motor vehicles is described, two measured variables are derived from position data from two object position-finding systems of the vehicle that operate independently of one another, for an object located by the two position-finding systems, one variable for each position-finding system, these variables representing one and the same physical parameter, and the two measured variables are then checked for consistency, which is characterized by the fact that the parameter is the time to collision of the vehicle with the object, which is calculated in advance.

Abstract: A method for displaying a warning message in a first vehicle, includes transmitting from a second vehicle a warning and position data relating to a position of the second vehicle to the first vehicle, wherein if, after reception of the warning and of the position data by the first vehicle, it is concluded on the basis of the received position data that the second vehicle can be seen by a driver of the first vehicle in a region of a head-up display of the first vehicle, the warning message is displayed in such a way that the second vehicle is characterized visually for the driver of the first vehicle in the head-up display of the first vehicle.

Abstract: In a method for operating a heads-up display system of a vehicle, the roadway state of the roadway to be traveled by the vehicle is checked using at least one suitable sensor, and a warning message is displayed at a location on the windshield in the case of detection of a critical roadway state, the location of the warning message corresponding to the dangerous, driving area of the roadway as viewed from the driver's perspective.