This paper focuses on investigating the performance of vehicular networks employing non-orthogonal multiple access (NOMA), wherein a base station (BS) situated roadside communicates with a pair of vehicles containing multiple antennas. To enhance the performance, maximal ratio combining technique is employed at the vehicles, leveraging diversity gain. Real-world scenarios, however, often deviate from the assumption of identically distributed channels between the BS and vehicles, impacting the expected system performance. To provide practical insights, the paper derives closed-form expressions for channel density functions, outage probability (OP), and ergodic rate of NOMA vehicular networks under independent and not necessarily identically distributed channels (INID). The analysis also incorporates the impact of time-selective fading to model the mobility of vehicles. Performance of the system is further analyzed through outage performance, rate, and sum-rate performance metrics at varying speeds of vehicles and decaying parameters of non-identically distributed channels. Simulations are conducted to validate the presented results. Additionally, the NOMA is compared with orthogonal multiple access (OMA) for vehicular networks. Numerical results confirm the superiority of NOMA over OMA under both independent and identically distributed (IID) and realistic INID channel conditions, emphasizing the robustness of NOMA across different vehicle speeds and non-uniform channel distributions.