Well my DD1 is 4yo and trained for over a year and we still ask her to wear a pull up for long car rides. I don't want her to have an accident if she falls asleep and I don't want her to tell us she has to go and have 50mi to the next rest stop. DD1 knows it's just there for an emergency and to tell us if she has to go (which she always does). So, I vote for diapers.
Mom to two amazing DDs ('07 & '09) and a fur baby.
Gluten free since Nov '11 after non-celiac gluten sensitive diagnosis. Have had great improvement or total elimination of: migraines, bloating/distention, heartburn, cystic acne, canker sores, bleeding gums, eczema on elbows, dry skin and scalp, muscle cramps, PMS, hair loss, heart palpitations, fatigue. I'm amazed.