You need to keep in mind that we in Switzerland are by nature anti-car and we don't go out of our way to facilitate cars, except perhaps in the Kanton of Aarau, but that is another story.
- In Zurich the number of the cars allowed into the city at any given time are limited. If you find yourself stuck at a traffic light on one of the motor ways, it is most often because you have to wait for a car to leave the city before you can continue.
- Traffic lights designed to ensure you rarely get two green lights in a row
- Limited public car parking
- Planing restrictions on the number of parking spaces hotels etc. can have.
- Local laws requiring hotels to charge guests for parking spaces
And so on.
On the other hand we have an excellent public transport system, which you should be able to use, if you get a little bit organised:
- As others have said, pack light and use a wheelie bag
- Ask hotels for assistance in pick up and drop off
- Use MapSearch to identify hotels that are within easy walking distance of the train station.
- On the train timetable at SSB, use the advanced option and change the transfer duration to say 10 mins, so all train options will allow you more time to transfer
- Also on the train timetable you can select the option to show only connections that are suitable for person with mobility issues
- You can also forward luggage you don't need to a train station and pick it up later
I have mobility issues myself, so I do understand where you are coming from, but I think if you do a bit of planning you'll have a lot less stress on your trip to Switzerland if you take public transport.