There are a number of options to choose from but we would suggest basing your decision on the specific needs of your parents. A large estate car such as the Skoda Octavia or Superb has good access, but if you need something a little taller then an MPV such as the Citroen C4 SpaceTourer or SEAT Alhambra might be a better option. For the best possible access at the lowest price, you may wish to consider a van-derived vehicle such as the Ford Tourneo Connect or Citroen Berlingo, which have tall openings and sliding rear doors.