Q: Why does my car automatically slow from 70 mph to 60 mph on its own 2003 Honda Element

Hi there. This can be caused by a number of things. I would first check to see if the check engine light is on and if there are any codes in the system. If there are any codes then it can shed some light on what the computer is seeing as the problem. If there are no codes in the system then further testing will need to be done. It sounds like there may be an issue with the throttle body failing or possibly a clog in the exhaust like a failing catalytic converter. I would have a certified mechanic check it out, like one from YourMechanic, that can come to you to [diagnose why the vehicle is losing power] https://www.yourmechanic.com/services/loss-of-power-inspection