We have to drive almost 2,000 kms (1,240 miles) to get to the top of Denmark for our ferry crossing to Norway June 1st. And we have 18 days to do it in, so that's an average of 110 kms (68 miles) per day.
Easily doable, but of course we want some rest days in there as well. And we try to keep our driving days under 200 kms (124 miles). We're trying to avoid the motorways and toll highways as much as possible.