I don't know if Irene has managed to find a solution, but as I have several different people in the family with mobility issues, perhaps these points may help her or anyone in a similar situation.
We bought a Focus estate for the wheelchair friendly boot, without a lip, and the low seats. Those high people carrier types may have lots of room in the back but are hopeless for little old ladies who can still manage to get into a car.
To assist those little old ladies to get into the car, we put a simple plastic carrier, the bag for life sort, on the seat. Then it is easy to swivel from the side to the front of the seat.
We have a Honda Jazz in the family. The main problem with loading the wheelchair is the lip. This has been sorted by adding a sort of false floor, initially we tested with just a pile of wooden blocks to see if the idea would work! The chair is loaded folded, but vertical, by resting the back wheels on the ground, lifting the front up by pivoting on the back wheels, then lifting the back wheels and rolling forward. The chair is secured with a bunjee to a ring at the side of the boot. It's much easier than it sounds, as at no point do you have to take the whole weight. Putting the brakes on makes it easier, and sometimes folding the handles down just before the final push.
A few years ago we accidentally discovered TGA powerpacks, https://www.tgamobility.co.uk/range/pow ... erpack-duo
which are powered wheels that are added to a manual wheelchair and crucially are operated by the pusher, essential when the passenger is blind as ours is. They are often available on ebay for a fraction of the original price. It takes a couple of minutes to fit to the chair each time, only the first time is a bit tricky! Then, you have help to push and it makes life so much easier. It comes apart easily and each piece is not too heavy to load. An absolute godsend, I wish we'd known about them 20 years or more ago.
Hope some of this helps someone.