It is located inside the Air Cleaner Housing in the engine compartment.
To replace the Air Cleaner Element remove the housing cover. Remove the old air filter. Clean the inside of the housing. Place the new Air Cleaner Element. Install the housing cover back into place.
For pictures or more details follow the link bellow to the 2000 Honda Insight Owners Manual and go to the Page 173 using the arrows in the upper right corner
Hello, I am sorry the instructions above are for the Engine Air Filter Replacement, and I believe your are looking for the Air Conditioning Filter or Cabin Air Filter on your Honda Insight. The Air Conditioning Filter should be replace every 2 years or 30,000 Miles under normal conditions and it is located behind the glove compartment, You will need a Standard screw driver and a Phillips screw driver and follow the instruction on the link bellow, Good luck!