In settings a person can set one of the two trip computers to reset manually - once you have this set up you can reset that trip meter by pushing the reset button on the end of the turn signal lever.Odd I find it only resets when you manually reset it, I wish it would reset on fuel fill-up like my Acura's did. The Acuras have 2 trip computers, A which rests on fuel fill up and then B which never resets unless you manually do it. I wish Volvo did the same. And on the P8 something similar, offer 2 trip meters, one that rests when you charge to your defined max charge SOC and the other that is manual. The auto meters on the Volvo seems to use some magical 4 hour period of non-use to trigger a reset.
I thought I remembered having to press it for a couple seconds after getting gas to reset the mileage on the manual odometer, but not as long as to reset the MPG and speed data (though I always do that too after each fill up). That's why I was puzzled by the manual odometer resetting to 0 between fill ups. But again, I guess it IS still possible we've occasionally been resetting it while using our direction arrows.The button has to be held for like 2+ seconds to reset the trip computer.