What is the ruling on an engineer working on government projects asking contractors to provide work necessities—such as cars and computers—and what is the ruling on using some of them for personal purposes?

If the contractor pays something willingly, there is no harm. However, obliging him to do so without entitlement is a form of consuming wealth unjustly, as Allah Almighty says: "And do not consume your properties among yourselves unjustly," and the Prophet, peace and blessings be upon him, said: "Every Muslim's blood, wealth, and honor are sacred to another Muslim." The fact that the contractor's profit might cover these expenses does not justify consuming his wealth unjustly. The prohibition and sin become more severe if these things are used for personal purposes unrelated to the work.