Clear Lake to Iowa City

Most if not all is divided highway, though not necessarily limited access (i.e. there may be grade crossings). It goes by various numbers, US281, and I380 (branch off I80) cover most of it. It is part of a Saint Louis to Saint Paul corridor, developed in part to serve the large Walmart distribution center in Mt Pleasant (south of I80). Zoom in far enough and you will see it has bypasses in most towns.

I had trouble finding route 27 on Streets & trips until I zoomed way in. We have used that route twice driving from the Winnebago Factory at Forest City IA to Iowa City. Streets & Trips shows it as route 18 from Clear lake to Waterloo. We then picked up I380 to Iowa City. If memory serves, it is all good divided highway. No stop and go likely unless you hit rush hour in Waterloo or Cedar Rapids.