Shift-by -wire technology enables new gear shifter designs in cars. Highly innovative gear shifter designs might confuse drivers and have a negative impact on usability. However, new designs might also be more intuitive and easy to use. The purpose of the study was to identify possible usability profits and concerns with different types of gear shifters with shift-by -wire technology during natural interaction, as in a car rental scenario. Four gear shifter types were tested: a button, rotary, joystick, and a stalk shifter, from a usability perspective. The joystick shifter was the most preferred shifter, it felt familiar. The button shifter was the easiest to understand and use. The rotary shifter had also high ease of use apart from one task, the activation of the manual driving mode. The stalk shifter was the least preferred and also the most difficult to use

Over the last few decades, the development of technology used in cars has moved forward at a very intensive pace. The focus has started to shift from the technology to the human as a user. The work done earlier regarding, for example, driver’s capabilities to process information, has now become a focus when developing modern cars in order to make driving more safe, efficient, and pleasurable. With increased knowledge comes new questions. With advancing technology and opportunities, questions about the user and how to adapt the technology to humans has become increasingly detailed and complex. One of these technological devices is the novel gear shifter used in passenger cars. Today, there is a transition taking place. Traditional gear shifters, which use a mechanical connection to the transmission, are being replaced by gear shifters that rely on electronic systems. This will allow for greater variation in both the function and design of modern cars. However, there is still a lack of knowledge about this new technology; we know little about what effects these variations can have on users. The aim of this thesis is to contribute with knowledge regarding this new technology by studying the conditions for technological development in general and the usability of modern gear shifters in passenger cars in particular.

One field study, two laboratory studies and one interview study will be described in this thesis work. The field study, which was conducted with traditional shift-by-wire gear shifters, showed that the joystick shifter was the most preferred gear shifter type since it was familiar, however, the largest number of errors was made with the joystick and stalk shifter. Familiarity and the car environment seemed to influence the overall acceptance and attitude towards the gear shifters. The second and third study showed evidence of driver difficulties with the monostable gear shifters. Difficulties concerned the lack of dedicated positions, which withdrew both visual and haptic aid for the driver and could presumably increase the driver’s cognitive load, causing the driver to feel lost in the shifter pattern and to direct too much attention towards the gear shifter instead of the road. Participants described how extensive use of gear shifter modes that are lined up in a row could be cognitively demanding and that the single fixed position of the gear shifter did not provide the type of haptic or visual feedback that could help the driver become oriented with the shifter pattern. The third study compared the performance of the gear shifters in younger and older participants. The older participants made more errors and had longer task completion times than the younger participants. However, the older participants rated the gear shifters with higher ease-of-use scores than the younger participants. The older participants seemed to learn how to use the polystable gear shifters quite quickly, but not the monostable gear shifters. The fifth paper used a different approach and methodology to describe the complexities of decision-making in the Swedish vehicle industry. It revealed a situation where decision-making was a balancing act between normative and descriptive decision-making, often dependent on available knowledge and guidelines and whether there was time and money to acquire new and complementary knowledge. If resources for knowledge acquisition were lacking, social networking was described as a way to compensate. Well-functioning communication between teams and key actors in the development process was also revealed to be crucial for efficient decision-making. Also, a more agile way of working has the potential to impact decision-making due to different resource requirements for hardware and software.

Shift-by-wire technology enables more options concerning the design, placement and functions of gear shifters compared to traditional gear shifters with manual transmission. These variations can impact usability and driver performance. There is a lack of research regarding the potential advantages and disadvantages of different types of gear shifters. The purpose of this study was to investigate the efficiency and subjective ease-of-use of mono- and polystable joystick gear shifter types at different complexity levels and with full or limited visibility. An experimental study with 36 participants was conducted. The results showed that monostable joysticks, especially those with an I/J-shape, were overall less efficient and easy to use than polystable joysticks. The highest complexity level clearly affected the efficiency for the monostable joystick with an I/J-shape (mono I/J) compared with the other gear shifter types. The monostable joystick with an I/J-shape (mono I/J) was also most affected by reduced visibility at the highest level of complexity, indicating that it was more prone to causing users to take their eyes off the road.

Shift-by-wire gear shifters are increasing the opportunities for individualization of functions and design. Though, greater variations can make gear shifters inefficient and error prone. Research regarding these aspects is still lacking. The aim of this study was to investigate how different gear shifter concepts were perceived in terms of Perceived Ease-of-Use and Task success, depending on their level of complexity, the shape of the shifter and stability of the shifter pattern. An experimental study was conducted with participants using six types of gear shifters on three levels of complexity. Results showed that the Monostable joystick received the lowest Perceived Ease-of-Use scores. Furthermore, the Rotary Toggle shifter with monostable function, had lowest Task success, which was supposed to be a result of e.g. unfamiliar design.

Incidents with monostable gear shifters in passenger cars have been reported to the National Traffic Safety Administration. Studies have also shown usability issues with monostable gear shifters in cars. However, these studies have focused on younger adults. The aim of this study was to evaluate whether usability testing would show a difference in a comparison of older adults and younger adults in a study of the possible effects of age on gear shifter usability. Two age groups were compared, with 12 adults between 19-31 and 12 older adults between 51-66. Task completion times, task success and perceived ease-of-use were measured with six different gear shifter concepts, with a joystick or rotary gear shifter, and with variations in movement patterns in different levels of visibility. Results showed that the older age group had longer task completion times and made more errors than the younger group. However, the older group gave all of the gear shifters higher ease-of-use scores than the younger group. Overall, the monostable gear shifters received lower usability measures in comparison to the polystable gear shifters. There seemed to be a learning effect with the polystable gear shifters, especially for the older age group. This indicating that the polystable gear shifters were easier to learn than the monostable gear shifters, and that they were not as dependent on visual feedback.

Within industrial environments, a number of different decisions need to be made on a daily basis regarding product development. These decisions will have an impact on, for example, safety, efficiency and customer satisfaction in different ways. It is of interest to investigate how decision makers within the Swedish vehicle industry experience the line of action for making decisions and how they experience possible concerns and improvements in decision-making. Nine semi-structured interviews were conducted with different experts within the vehicle industry. The results showed that everyday decision-making is a balancing act between normative and descriptive decisions, often depending on available knowledge and guidelines and whether there is time and money available to acquire new and complementary knowledge. If the resources needed to acquire knowledge are lacking, one of the most important resources is networking, both internally and externally. Well- functioning communication between teams and key actors in the development process is also reported to be crucial for efficient decision-making. Also, a more agile work approach could impact decision-making due to different resource requirements for hardware and software.