Due to the pandemic, my Prius C has been parked in my garage for over a year with fuel tank full (with added stabilizer). It looks like this will last for another 6 - 12 months. Should I replace the old fuel with fresh fuel? The most straight forward way would be to drive it for a few hundred miles and then fill the tank up. But that means renewal of registration with DMV, adding liability/collision insurance coverage then cancelling it, taking the smog test, et. al. Another way would be to drain the fuel out. Either way would require a lot of work. Just wonder how long you have kept the fuel in the tank without issues?