You should check your car insurance to see if even allows you to use the car for business purposes. Many crew have found it is not covered, and your passengers and yourself are not insured.
Most airlines now recognise this and should provide you with a hire car with business use insurance. If you are currently using your car to position to other bases for work, I strongly suggest you stop and get your HR department to look into it.
Regards
Edited for content 14/07/03