  Automotive-Industry 5.0 will use emerging 6G communications to provide
robust, computationally intelligent, and energy-efficient data sharing among
various onboard sensors, vehicles, and other Intelligent Transportation System
(ITS) entities. Non-Orthogonal Multiple Access (NOMA) and backscatter
communications are two key techniques of 6G communications for enhanced
spectrum and energy efficiency. In this paper, we provide an introduction to
green transportation and also discuss the advantages of using backscatter
communications and NOMA in Automotive Industry 5.0. We also briefly review the
recent work in the area of NOMA empowered backscatter communications. We
discuss different use cases of backscatter communications in NOMA-enabled 6G
vehicular networks. We also propose a multi-cell optimization framework to
maximize the energy efficiency of the backscatter-enabled NOMA vehicular
network. In particular, we jointly optimize the transmit power of the roadside
unit and the reflection coefficient of the backscatter device in each cell,
where several practical constraints are also taken into account. The problem of
energy efficiency is formulated as nonconvex which is hard to solve directly.
Thus, first, we adopt the Dinkelbach method to transform the objective function
into a subtractive one, then we decouple the problem into two subproblems.
Second, we employ dual theory and KKT conditions to obtain efficient solutions.
Finally, we highlight some open issues and future research opportunities
related to NOMA-enabled backscatter communications in 6G vehicular networks.
