Trying to understand the way your question is worded. Is this your car you are allowing them to drive or their car under your name?What does this do vs. letting them drive your car basically? I just make them primary on their respective vehicles.
If I am correct I think its their car under your name. My comment to the other person was that it is a "smart move" to have the kids vehicles under the kids name and not his.
The reason being is although rare, it does happen, being young sometimes big mistakes happen. Anything or anyone that vehicle that hurts, disables or kills someone or someones in an accident, you are the owner are responsible financially. Should the settlement be greater then the liability coverage they can then go after your assets because the vehicle is in your name.
Young people typically have less assets to go after in a severe situation like this.
Pretty much, if it can be avoided, it's always a good idea not to have a motor vehicle that you do not drive in your name.
Other things not realized, lets say your kids are super responsible and out on the town one night with their friends, have a designated driver who is not drinking and behind the wheel of your car and god forbid a terrible accident occurs, you as the owner are the responsible party and the one the attorneys will go after since you have the assets and own the vehicle.