I'm sure you checked this, but it's weird to me
in case of an accident of course the driver could be sued, and why not sue ALL owners. Which would be both of you.
Lots of other lawsuits do that where they shotgun the sue to include everyone and let people prove they are not liable.
I did look into it and confirmed it with our insurance agent. The premise is that the owner gave permission for a non-owner to drive the car and is, therefore, also held responsible for the actions of that driver. When 2 people own the car, both have permission to drive the car, as both own it. Joint car owners can't be held responsible for the actions of the other owner.
A practical example would be this: The older car is still in my husband's name alone. Our son is learning to drive, so he and I are both driving that car. If my son or I was driving and caused an accident, the driver and my husband (as owner) could be sued, because he gave permission for us to drive his car.
The newer car is owned by my husband and myself. He is currently driving it. If he caused an accident, he could be sued. I could not be sued, because I can't give permission for him to drive the car. Both of us have permission as joint owners of the car.
Another reason this matters is that in Ohio, each of us owns 50% of our jointly owned assets. In the examples above, with the older car, if my son was an at-fault driver, my husband's 50% of non-exempt assets would be at risk. If I was the driver, 100% of our non-exempt assets would be at risk. With the newer car, as long as only my husband or I was the driver, only 50% of our non-exempt assets would be at risk. If we let our son drive the newer car, he could be sued and both my husband and myself could be sued as joint owners of the car, putting 100% of our non-exempt assets at risk.
We do have an umbrella policy, so that would mitigate matters a bit, too.