Is selling comprehensive car insurance and taking commission for it forbidden or permissible, given that it is mandated by the company where the questioner works at a car dealership?

Commercial insurance is forbidden, while cooperative insurance is permissible. If the insurance you are responsible for is cooperative, then it is permissible to work in it and earn from it. However, if it is commercial, then acting as an intermediary in it is not permissible, regardless of whether it is comprehensive or not, or optional or compulsory.