Is this grammatically correct, "No, car insurance cant be used as?
It is grammatically correct but poorly drafted. Replying fully is difficult since you give no context. How about this: A motor vehicle insurance card cannot be used as proof of address. Proof of address is limited to a utility invoice, e.g. water, electricity, gas, internet services, landline telephone or cable services. (What is not stated is if a property lease or deed of trust is acceptable.)