Remote Keyless Entry (RKE) systems have become a standard feature in modern vehicles, yet their unidirectional fixed-frequency radio communication renders them vulnerable to replay attacks, impersonation attacks, cryptanalysis, and intentional interference. Existing cryptographic authentication methods enhance security but often fail to address real-world constraints such as computational efficiency and radio interference. To mitigate these threats, we designed the Adaptive Frequency-Hopping Algorithm and the Adaptive TXP and PHY Mode Control Algorithm that can dynamically optimize channel selection, transmission power, and PHY modes based on real-time channel quality assessment. To enhance the security and reliability of RKE systems, we propose the Lightweight Vehicle-Key Authentication Protocol. In addition, a prototype of the proposed scheme was implemented to verify its effectiveness in mitigating interference and preventing unauthorized access.Experimental results show that our scheme significantly enhances communication security and reliability while maintaining low computational overhead. Under mild interference conditions, the packet delivery rate (PDR) of the adaptive scheme increases from 93% to 99.23%, and under strong interference, it improves from 85% to 99.01%. Additionally, the scheme effectively prevents replay and impersonation attacks, ensuring secure vehicle access control by dynamically optimizing communication parameters to maintain stable and reliable transmission.