We have a very narrow driveway and are thinking of buying a seven-seater to house two children's car seats (one three-year-old and one newborn) and two adults and luggage most of the time. Occasionally, there's five adults and the two child seats. One adult is small and mobile (e.g. can climb over and sit in a small space) but two of the adults are elderly with very limited mobility. We were thinking that one with sliding doors would help with our narrow drive situation (brick walls on either side). Even on our Ford Fiesta, we can't open both sides fully and therefore it's difficult getting young children and elderly adults in and out. We're also looking to buy secondhand. What should we look at?