We checked under the driver side carpet, remove the plastic cover on the side but there's nothing "removable" behind the plastic cover. Is it under the hood?
Where is the cabin air filter and how do you change it on 2000 Lexus ES300
The White plastic cover close to the firewall to the right of the gas peddle is the way to access the cabin air filter. The two piece filter, if installed should be directly behind the cover. After cover removal, pull out first half filter, then pull tab at the top down and then out to remove second half. Re-installation is reverse order.