Thre are some errors in the Newton Car demo, I dont know if you are using some newton demo to start your project. The Collision Detection is using the same skill as Max_Speed and that caused Newton Cars dont collide between themselves.

I think you can get your bullet, and try to assign a newton material to it, like Newton Wood, but I dont understand how you will make your bullet collide with the player. I suppose you want to make your model "Feel" the impact of the bullet and fall in the ground or something so.

I dont know exactly how you can do it, but I think, if you are using newton :

1) You can very easyly add a force to the bullet body and make it be launched at high speed in your level.

2) YOur model will be hitted by the bullet, but I really dont know if it will react to your bullet going doiwn or somthing so. Maybe this will need animations and some code. Probably the bullet will pass through your model´s body.

3) You can assign some animations to your model and detect by code if the bullet hit the player. if so, change the animation to the one that fits the impact. Then get the bullet out of physycs simulation and remove it.

This are only basic ideas, in fact i´m not so experienced to tell you exactly what to do.

But hope this can help, or someone else more experienced can point something also.

4)