How long do major rental car companies keep their cars before selling them?

Does anyone know the standard for how long a rental car company such as enterprise, hertz or avis keeps their units before selling them? I’ve noticed throughout my travels that none seem to be more than a year or two old, and none have over 30k miles.

How does rental car insurance offered by credit card companies (when you use the card) work?

I have credit cards which say they cover me for rental car insurance when I use the card to make the full payment for the rental. How does that work? Are there any catches? Does it make sense for me to get the additional insurance from the rental agency (like Read more