My friend brought a car, we have lived together for 5 yrs, he wants me to sell my car, which is in my name only , and put title & insurance in both our names, we are retired and in our late sixties. What problems would there be if one of us would die , would the car go to the survior, or would half go to his kids, as they are named in his will to get everything right now. I have no intentions of getting married to him at this stage in my life.

Depends on how you title it, and what you have in your will.
A couple not married, has no inheritance rights, so unless the title was in joint ownership with right of survial ( if allowed in your state) yes his 1/2 would go to the family.

So remember look around your home and every item that is yours or his had better be named in the will, since his family will be wanting everything out of your house if he passes first claiming it was his.