As we all know the CT200H like the Prius has two batteries, a 12 Volt like all cars which powers lights and aux equipment and the gasoline engine and a high voltage lithium ion battery which drives the electrical motor part of our hybrid. An issue for many is how long the high voltage lithium ion battery, which I will call the hybrid battery, will last as it is rather expensive, USD $1000.+, to replace. I recently learned that a major key to how long the hybrid battery will last is keeping it from over heating. Makes sense to me that if the battery overheats then it will be degraded if not damaged. And if it continues to overheat it will eventually die. Apparently, if one can believe the internet stories, a key component to keeping the battery temperatures within reason is a cooling fan located on the right side of the car behind the passenger seat. There is an air intake vent by the right hand passenger's seat. If this vent is covered or closed off the battery can easily overheat. Further dust, dirt, pet's animal hair or whatever can be sucked down into the fan and cause it to lose it's cooling capacity or fail. Apparently latest model Prius have an air filter to keep the fan clean. Is this true for the CT200H as well? And if not, why not. My understanding is that if the battery is NOT subjected to overheating it can easily last 200K-300K or more miles. And apparently cleaning the fan is now being included as a service albeit a rather expensive one, USD $350 or more.