I was glad when he said that his car was ............

- at your/somebody’s disposal: tùy ý ai sử dụng 
E.g: He will have a car at his disposal for the whole month.
I was glad when he said that his car was at my disposal.
Dịch: Tôi rất mừng khi anh ấy nói rằng chiếc xe của anh ấy là tùy ý tôi sử dụng.