If I place a rail (any type) and a minecart on top (any type) and move the rail with a piston (that is placed one block away), the minecart will turn.

How I did this:
1. Place a rail (any type will work) facing nourth-south (default rotation)
2. Place a sticky piston with one block space between the piston and the rail (see img1)
3. Place a minecart on the rail (see img2). Any type of minecart will work
4. Power the piston (img3)
5. When the piston moves the rail (when retracting) the minecart will change facing to east-west (img4)