Always hold the box from the bottom, never from the sides.
Place the cake on a flat, stable surface, ideally the floor of your car or the trunk (as long as it receives A/C). Do not place the cake on a seat or on your lap, as body heat can affect the structure and finish.
Keep the cake level at all times and avoid sudden stops or sharp turns. Make sure the car is cool (A/C on), especially in warm weather, and keep the cake inside its box until you reach your destination.
Storage:
Both buttercream and fondant cakes should be stored in the refrigerator until ready to serve.
Before Serving:
For best taste and texture, remove the cake from the fridge 1–2 hours before serving, depending on the room temperature.