Many comprehensive insurance policies cover items like car audio systems, or roadside assistance. These can raise the premiums, so only get them on your policy if you really need them. Check out to see if your norwich union car insurance online, can give you a discount if you don't require them.
If you have expensive in car entertainment make sure your car insurance policy provides enough cover to meet the cost of replacing it and it has been declared on the application form, if it is not standard equipmenty in that car.
A fully comprehensive car insurance policy will cover any personal injuries to third parties including your passengers as well as your car and theirs, in the case of the accident being your fault, or no balme to either side.