You "can't expect baby to sit that long," how old is the baby? If the child is an infant, all she will probably do is sleep. Cars are pretty lulling.
She's a toddler. Even then I know I need a break and to spend some time with just my husband.
Then she will handle it. She probably likes her grandma.
Right now I am 36 week pregnant and i can totaly understand ur situation. me n my husband desperately looking for a break after arrival of baby...