A 323 sedan, and a 12" dob. WOW!
Roof racks are not a good option. It really, really isn't. Too much of a risk for the primary mirror. The cushioning that the interior of the car provides makes a HUGE difference.
I know that is a pain in the bum to load the scope into your car, but it really is your best option to safely transport the scope. A Hatchback 323 is a better option!
I had one too
The only other options other than a better suited car is a different scope - Yeah! I bet that's
REALLY what you wanted to hear!
A collapsible 12" dob, or a smaller scope. Or you rebuild your 12" into a collapsible truss/strut scope. That's what I ended up doing with that 17.5".