What is the ruling on money acquired from government work that includes irregular overtime hours, "savings" from projects achieved through deficiencies in contract clauses, financial bonuses not based on a specific system, and the use of work vehicles for personal purposes?

There should be no financial relationship between the project supervisor and the contractor because it corrupts the supervisor's performance of his duties and breaches his trustworthiness. However, there is no harm in taking the agreed-upon supervision fee from the contractor if it is stipulated in the contract, and the contractor's request to work overtime should be accommodated.

The supervisory body must fear Allah in their work, so they do not wrong themselves, the contractor, or the employer. The estimation of materials must be accurate and conform to the needs, and any surplus beyond the work's requirement should be returned to its owner, unless the regulations make it a right of the supervisory body.

You are not required to inquire about the source of money granted to you as a reward unless you are certain or highly suspect that the money is unlawful.

There is no harm in using the car with the approval of the senior management.