You don't give the age of your car or say if your car was upgraded from the original factory BMS to the latest Jan 15th 2021 update.
It has covered only 5,000 miles, so assume it if a recent purchase or a low usage car.
If you returned 163 miles after a full charge and balance from day one, then your car was already supplied with the NEW update already applied.
Well done that dealer !.
You appear to be carrying out a full charge and balance cycle correctly and resetting your trips to get a more accurate GOM reading.
I can feel that you have already checked that you do not have ANYTHING running in the back ground, at the time you are checking your readings of course ?.
I think what you are reporting is fairly conducive to what other owners are witnessing.
@JodyS21 has huge majority of the information compiled regarding battery behaviour etc.
Lower ambient temperature DO effect a number of things, like range and the power of Regen and the speed of the charge entering the pack etc.
But I don't think it should reduce how much capacity you can get into the HV battery ?.
Other factors at play I think.
My guess would be here, that the return figures you are seeing now, will become the new norm in most cases.
My car had the update on almost the same day as the update was released, 15th Jan 2021 !.
When returned, the car reported 449 - 450 volts and 162 - 163 miles of predicted range after a full charge and balance.
After about six months (ish) it now returns about 148 - 149 volts on the pack, with a predicted GOM mileage of 155 miles.
Other owners who have covered similar mileages ( 16,000 miles over nearly two years ) are now seeing similar results.
That reminds me, I do need to carry out another full charge and balance, to see if there has been any shift in these figures.
I just don't like charging to 100% if I don't have a big enough trip planned, in order to use the high capacity stored in the battery.
I not a big fan of charging to 100% and then leaving the battery sitting bursting at the seams with no place to go !.