Not to be difficult, but if you don't like walking in freezing temperature, why come to Oslo in January? Personally (and having now lived here for a few years) I find the month awful alongside equally awful February and November...

I live near Sommerro as well, and have stayed there. The hotel feels big, the check-in area whilst off the lobby, a little chaotic. Given how social Sommerro is (in my view it is a restaurant and bar for the neighbourhood, and a hotel too...) I am per se not sure I'd want to stay there if you want true luxury (and perhaps contrary to what I said yesterday). Personally, I prefer 100 rooms hotel max (give or take), a good bar that is happening but overall feeling of tranquility. Sommerro does not have a good bar in my view (whilst the main dining hall bar is good, it is somewhere you go, but not necessarily relax), and too many food offerings for a hotel (ie they're dependent on outside guests). Breakfast at Sommerro is very good, and if you're a vegan / vegetarian, probably the best breakfast spread I've ever come across.

I think the Continental room upgrades are a bit dated (ie they were at time of completion) but believe they come in two styles. Agree that the breakfast room is dark. Last time I had breakfast there I found it dirty and really not 5*. Service I've always found to be very good (when adjusting for Oslo service...) and in my view, their hotel bar is probably the most continental (no pun intended) of bars in Oslo.

I think I would look at Villa Inkognito at Sommerro (they also have a separate bar for the villa, own breakfast chef etc...).

I don't think any hotels really operate with house cars but can probably book a car service for you.