# Internet of Vehicles for Sustainable Smart Cities: Opportunities, Issues, and Challenges
## 2 Global Market/Bibliographic Data Analysis and Standards  
The global IoV market is expected to experience significant growth over the forecast period, from USD 145.24 billion in 2023 to USD 678.94 billion in 2030, at a compound annual growth rate (CAGR) of 24.65%. In 2020, the market size was USD 85.12 billion, but it witnessed a negative demand shock across all regions due to the global impact of COVID-19. This resulted in a substantial decline of 10.72% compared to the average year-on-year growth during 2017-2019 [41]. The IoV industry is anticipated to benefit from advancements in technology, connectivity, and the integration of vehicles with the Internet, leading to improved safety, efficiency, and convenience for consumers. It is important to note that the figures mentioned are based on projections and should be interpreted as estimates for the future growth of the global autonomous vehicle market [42] as depicted in Figure 2. Market conditions and various factors can influence the actual growth trajectory, so it is essential to monitor industry trends and developments for a more accurate assessment. Furthermore, the bibliometric analysis centered on IoV in the context of smart cities, utilizing data sourced from the Scopus database. This study investigates the trends, contributions, and impact of research on IoV in smart cities from 2012 to 2025. This approach ensures that researchers are presented with the most current research developments in the field enabling them to stay informed on emerging trends and advancements. Ultimately, 1514 articles were exported with the search query \"(\"smart\") AND (\"city\") AND (\"Internet\") AND (\"of\") AND (\"Things\")\" in English language and saved in CSV format before being included and examined in the bibliometric study. Articles were the primary type of publications analyzed. Visualization analysis was carried out using VOS viewer software 1.6.20, helping to focus on research areas that require further exploration in the IoV and smart cities domain. This bibliometric analysis offers valuable insights for researchers aiming to research unexplored areas within the domain of IoV and smart cities. In this data analysis, the yearly distribution of publications is examined, highlighting the substantial growth observed in this field. Significantly, the year 2021 stands out with the highest number of publications, reaching 98. Articles dominate the document types, constituting a significant 71.7% of the publications.  
Figure 2: The global autonomous vehicle market size, 2022–2032 (USD billion). Reprinted with permission from Ref. [42].  
When considering the distribution of documents by source, IEEE Access emerges as the leading source, contributing over 15 publications. In terms of subject domains, the field of engineering leads with the highest number of publications at 33.6% of the total, closely followed by computer science, which holds the second-largest share at 26.9%. Figure 3 displays the clustering of keywords frequently appearing together within research papers. It visually represents the connections between co-occurring keywords. Significantly, \"Internet of Things\", \"Internet of Vehicles\", \"electric vehicles\", and \"mobile communication\" are the keywords that tend to co-occur most frequently in the research papers.