You can not testify all you want, but you should still be on the hook for your vehicle getting tickets, just like you are on the hook for your vehicle accruing toll fees.
If your car was magically stolen and returned, and you have no idea that it happened, or who could have done this... Well, that's certainly an interesting legal argument that you could make to a judge. I doubt he'll believe you.
In the old days it certainly happened. Joyriding. Take someone's vehicle for a spin, put it back. Illegal but nowhere near as serious a penalty. Car security systems have gotten a lot better since then.