If you do cosign an autoloan, there are things you can to mitigate your risk.

1.  Make sure they are buying a cheap and reliable car.

2.  You make the payments and it would be good if you could afford to if they can't give the money.

3.  Have control of the title so you can repo or sell the vehicle at the first sign of trouble.

4.  Accept the fact that this could damage your relationship down the road.