One car for many years. That is tough as your needs over the years will change and not all those changes can be predicted. I’m going to suggest that you get a small economy car now and put the difference away for a future purchase.
As a retiree, I find some issues with the available crop of vehicles. Few cars have the seat at the right height above the ground to make getting in and out easy. Add to that that the roof line is ALWAYS too low. That does not seem apparent to most people when they see all those tall SUV’s and crossovers out there, but the problem is that as the roofline goes up, so does the seat so you always end up twisting your head in order to get into the vehicle, even when you need a stepladder to get up to the seat.
There are some taller cars like the Subaru Forester that have a seat that can be adjusted for height, but only in the top of the line model. This is the car I would recommend for your though for a number of reasons, reasonable reliability, economy and AWD. BTW, the Ford Escape I believe has this as well but only in the top of the line. You need both front seats with this feature, not just the drivers side, and to get this in the Escape, I think you also have to get the Eco-boost engine, you might not want that engine in your situation.
The only issue with this vehicle will come if you ever need to “ride everywhere”, meaning one of those scooter chairs or a wheel chair. At first, you will be able to get by with a hitch mounted carrier, but eventually you may need a van. It is possible that you never reach this stage and in many cases, when you do, you won’t be driving anymore. That is when the money put aside will be needed.
Car makers out there, ARE YOU LISTENING.