## 1 Introduction  
According to the World Health Organization (WHO), over 80 million people require the aid of a wheelchair (WC) to gain mobility [1]. In the UK alone, 1.2 million people are wheelchair users (WU) [2]. To maximise participation of individuals with restricted mobility, it is important they undergo some sort of training [3], especially during initial rehabilitation for new WUs [4]. This sort of training enables WUs to drive the wheelchair safely, to manage their daily activities and, therefore, to improve their independence [4, 5, 6]. Moreover, training enables WUs to avoid being placed in long-term care facilities [7, 8], participate in society [7, 9, 10], and return to work [7, 11]. A training system should be comprehensive, including everything from learning to drive a wheelchair to learning to drive an adapted car, both of which play a crucial role in making a positive change in one's life [12]. For example, some studies have shown that those who travel further and longer in a day with their wheelchair were more likely to be employed [13]. An appropriate training system may also reduce the physical risks someone faces when driving a wheelchair without prior experience. In fact, driving a wheelchair can lead to injury to self, due to prolonged seating or loss of balance, injury to others, due to collision, and the destruction of the wheelchair or nearby objects [14]. These physical risks further stress the importance of undergoing wheelchair skills training. In this respect, various training methods have been developed, including training in real environments and in virtual reality (VR) environments [15]. To train a new wheelchair user in real life, programs include allowing the user to drive through various controlled environments such as obstacle courses or following a track on the floor [15; 16; 17; 18], and through uncontrolled environments such as rehabilitation centres, homes, schools, outdoors, and having the user interacting with the environment, like approaching objects [15; 19; 20]. However, the training of WUs has also been standardised using the wheelchair skills training program (WSTP) [21]. The WSTP is a training method that provides a standardised way of enhancing and assessing the skills of a manual or powered wheelchair user; it tests the WUs on individual tasks (e.g., driving straight, backwards, through obstacles, turning, etc. ), which allow users to deal with various real-life situations such as going shopping [21]. In this context, two review papers [22; 23] analysed the effectiveness of the WSTP compared to other real-life training methods for both manual and power WUs. Real-life training methods are often time and resource-intense [24; 25], rarely allowing individuals to drive through uncontrolled environments, as would happen on a day-to-day basis, and encounter the danger of collisions. These limitations are something VR training can mitigate [24]. VR is a set of technologies that create a world beyond physical reality. Consumer-grade VR systems can deliver experiences that are: non-immersive (via monitor screens), semi-immersive (using systems which project virtual environments onto walls), or fully immersive (utilising head-mounted displays HMDs). HMDs can be mobile or stationary, and are typically controlled using handheld controllers [26]. In specialised contexts, such as those for wheelchair skills training, alternative VR controllers have been developed that are tailored to users' specific needs, including wheel-mounted sensors [27], eye-tracking devices [28], or electroencephalography (EEG) signals [29]. By aligning with an individual's motor abilities, these methods enhance accessibility for a wider range of users. Training wheelchair skills in VR environments can have a number of benefits: it can be more motivating, it has lower risks [30], it increases safe and independent learning opportunities, and it enhances engagement with tasks [24]. VR has also been successfully used to simulate the driving of other vehicles such as cars, trains, and aircrafts [31].