If you want to manage assets such as a car, house, silver/gold deposits with MoneyWiz as a net value i.e. have them included to your Net Worth, you can create a Savings account and register the current monetary value as the Opening Balance.
MoneyWiz 2.0.x cannot automatically refresh the value of the shares or calculate for the amortisation of the assets, though. This is something that we are working for a long time, and will make available in one of the upcoming updates. Maybe later this year.
What you can do in the meantime is to register the gains on investment accounts as Incomes and the losses as Expenses, so you can see the big picture, or use Adjust Balance to reflect the total value. Same goes for amortisation, if you want to keep history of how the value decreased. If you simply want to see that your Net Worth decreased, say your car has passed 100,000 km, you can simply Edit the account and change the Opening Balance to the new value. The initial cost of the car, presumably will be reflected as an expense on another account, and there you can see the original value.