## 1 Introduction  
Traffic- and vehicle-related information are displayed by individual means in vehicles and by collective means on the roadside (visible through the windshield) [1, 2, 3, 4]. The motor vehicles are equipped with indicators and instruments positioned on the instrument cluster (IC) and on the central console as part of the human-machine interface (HMI). Driver-Vehicle Interface (DVI) is the more commonly used term because the term HMI is not limited to vehicles. Ergonomic aspects of information displays for navigation, Transport Information and Control Systems (TICSs), Intelligent Transportation Systems (ITSs), touch screen controls, and Advanced Driver Assistance Systems (ADASs) warnings and the design of the system's safety are in the current focus of the regulations and research [5, 6, 7]. One of the reasons is the trend to transfer more and more information from outside the vehicle (roadside information means) to in-vehicle traffic information services [6, 8]. The instrument cluster consists of instruments, displays, and indicators that provide the driver with various information. Although, in fact, there are no restrictions on the type and range of information provided, a cluttered instrument cluster (information noise) and/or unfavorable display characteristics lead to long glance duration and/or may cause difficulties in finding appropriate information. This leads to distraction from the primary driving task or results in misreading or misunderstanding [4; 5; 6; 9]. Individual instruments or indicators must not have too complex graphics, small size, low contrast, rapidly changing information, etc. [5; 7; 6]. The time period required to take the eyes off the road to the instruments, reading, and understanding the information should be as short as possible [5; 6]. The research of [PERSON] et al. (cited in [1]) showed that the average time to read the speed from an analog speedometer (a moving pointer on a fixed scale) is about 0.5-1.2 s. In the research of [PERSON] et al. (1998), presented in the report [5] (Chapter 12, p. 75), it was estimated that transit bus driver has a speedometer gaze frequency at a rate of 45 per hour and a mean duration of 0.65 s. [PERSON] et al. [6] stated that glances to collect relevant in-car information should not last longer than 2 s. The Standard ISO 15005 set an upper limit of 1.5 s for TICS [10]. Accordingly, the design and content of the automobile instrument cluster is a compromise between providing information to the driver and distracting attention from the driving task. However, style and technology are also factors that influence a final IC design. Vehicle speed is a dynamic variable, and this information must be available to the driver at any given moment [5; 8]. Every motor vehicle must be equipped with a speedometer, which is the most frequently used instrument in the vehicle [1]. The speedometer is placed on the instrument cluster within the primary field of vision, and it must be clearly legible both day and night [1; 2; 5]. There are two types of speedometer styles in modern vehicles in terms of the visual presentation of the vehicle speed [2; 3; 8]. The first one is the analog presentation, where the speed is indicated by a moving pointer and its position within a fixed round scale (pointer and dial). This presentation could be called a classic design. The instrument can be mechanical with a physical pointer or as a graphic on an electronic liquid crystal display (LCD). The second type is a numerical presentation of the vehicle speed (digital speedometer). There are also ICs that combine both presentation modes. Analog presentations have remained popular in the European market, while digital displays are preferred in the US and Japan [3]. Analog instruments should show better results in comparing speed values, such as \"speed is increasing\", \"speed is over the limit\", etc. On the other hand, digital instruments enable easier perception of quantitative results [2; 8].