I was really happy to find out that my new-to-me MINI performs very well in the cold - my last (very old) car was really reluctant to start or go anywhere once it got frosty out.

I do have one kind of odd issue, though - whenever the car is cold and in motion, I hear a rhythmic squeaking coming from the back. The squeak speeds up as the car speeds up and stops when I stop. Once the car's been rolling for a little while, the squeak goes away.

Is this normal? Or should I have something checked out back there?

 

I had same issue. It was my older runflat tires which were almost to the end of their lifespan.

To double check, rotate your back wheels to the front. If ths sqeeking moves up too, then you know it's the tire.

I suspect the tire is "walking" the rim during rotation. It drove me nuts on my MINI until I swapped them out.