To protect your users' data on your car rental website, use strong security measures like SSL certificates to encrypt data between your site and users, safeguarding payment details. Regularly update your website's software and plugins to avoid vulnerabilities. Use secure payment gateways that comply with PCI DSS standards for transactions. Provide clear website privacypolicies to inform customers about data use and storage, assuring them of responsible handling. Regular security audits and monitoring can also identify threats and strengthen your website security.