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.