I understand that the price in Norway is fixed in NOK, correct?
A weaker NOK is actually bad for Tesla's income statement, since it will translate into less USD per sale. Also as far as profits go, it doesn't matter when you paid for the car: If you paid for the car in Q2 but got it delivered in Q4, then Q2 currency has nothing to do with this sale on the income statement side for either quarter; it is the Q4 currency that matters. It is the opposite for cash on balance sheet though, but not the opposite for some other items on balance sheet (such as retained earnings). All of these things are sorted through a FOREX gain/loss account on IS. This topic is way too complicated to discuss, and it is really not that important to worry about unless currency movements are big. It is the average currency rate for the quarter that matters anyway for IS, and the difference in currency rate from first to last day that matters for BS.
The NOK only weakened 1% against the USD in Q4, so that will not be that big of an issue in Q4. The NOK has been pretty flat since deliveries started in Norway, and that is the important part as far as IS goes.
The important thing is that a weaker NOK is a negative for Tesla unless they are perfectly hedged (which is impossible to do), and as far as profits go it doesn't matter when you paid for the car - only when it was delivered.