It becomes even more complicated with the required infant seats and booster seats. Two infants, one double stroller leave no room and wouldn't fit in a medium size car.
Our son and his wife, our DIL, had a Ford Taurus with the first grandchild and with all of the gear needed for her, there was very little room.
So they went to an Explorer before their second child was born. My wife and I wondered why until we saw the infant seat, the toddler seat, the two baby carriage, the diaper bags and all the other stuff. Also the back end of the Explorer is a great place to change Pampers on a child. Throw a towel to cover the mat. Put the baby on the towel and change them standing up and not hunkered over like in a car.