New Highway to Sapporo
A new highway section has been opened between Furano and Sapporo that allegedly shortens the travel time by 20 minutes (usually 2+ hours). It also appears easier to drive. It is named the Bibai-Furano Line.
The section is officially an extension of Hwy 135, and is accessed from Hwy 452 near Sandantaki waterfalls, about 30 minutes from Furano. The section comes out at Bibai, which is on the E5 expressway to Hokkaido. This lengthens the drive time on the expressway by about 10 minutes, and will cost a few hundred yen more, but that is more comfortable driving than through the mountains.
Do a search for "Hokkaido Road Bibai-Furano Line" and a video should come up driving the whole section in fast mode. It looks much easier to drive than the notoriously curvy Hwy 452 to Mikasa--the usual way to get to Sapporo from Furano.
See you in Furano.