2. Start by fixing the engine. This is the main concern with a flood-damaged vehicle. If there is water in the engine, then you should not drive it. Instead, have it towed to an engine repair shop.
3. Drain the transmission and oil pans of the flood damaged car. Once they have been drained, you can replace the oil and transmission fluid.
4. Allow the brake system to be dried and inspected. Brake fluid also needs to be replaced.
5. Give the interior of the car time to dry out. It is likely that a mildew smell will linger once it has dried. In this case, take the car to an upholstery repair shop. They can rip out the old material, dry it out and replace it.