Must it be a sedan? If you would consider a small SUV or crossover vehicle, those often have easier access and more upright, chairlike seating. Many manufacturers have a few models that you should examine personally for fit. I suggest looking at the Honda CR-V, Subaru Forester and Toyota RAV-4. I was pleasantly surprised at the seating and access of the inexpensive Kia Soul.
You should strongly consider a power height-adjustable seat - not usually available on the base models of these vehicles, but often available on higher trim levels. A heated lumbar area might be more comfortable on long trips.