How to create realistic "sled behavior"?

For our current prototype we aim for a game element similar to the sliding passages in various 3D Mario games or the early Harry Potter games (see here or here). Basically a sled object moving down a mountain/slope based on the UE4 physics.

So far, so good. But however we configure our sled object, it keeps turning around its own z axis, instead of facing down the hill (the direction it is moving). What possible ways are there to prevent this or to create the “realistic sled behavior” in the first place?