Any diversions from standard auto insurance coverage are usually dealt with endorsements that are special conditions or permissions. They are usually sold as popular packages and several customizations need to be noted separately. They are called “riders” as well and the ways of documenting terms and conditions of additional arrangements between a motorist and a company.
When you have typical particulars and very common automobile things are easier and you can pick a package deal off the shelf, so to speak. However, often people have different requirements, vehicles are not standard or there is an issue with listed drivers. These things can be discussed so that an appropriate price is set for them and they get covered.
They are a good way of making sure your vehicle insurer knows about these particular issues. For example, family members (and others) who are living in the same household with you would normally be covered under your policy. They would take their details and include them when calculating quotes. This may result in high premiums (especially if that person has a bad record) for you for someone who is unlikely to drive the vehicle. In this case, you can strike a deal with the car insurance company to exclude this particular driver and keep the costs down. This would be dealt with an endorsement on the policy.
Another example is that you have done some modification to it and not only you want them to know about it but also you want to see that it is noted there. You talk to them and agree on an additional premium and get the automobile insurance policy endorsed to include the details of the alterations.
It is important that both parties are on the same page in terms of the facts of coverage. This would allow them charge a fair price and give you a peace of mind that all is out in the open. When there is a claim the company cannot back down or find a reason not to pay. It is a deal that works for both parties.
So, you can always discuss these extras or unusual circumstances with an agent. It is best that they know everything clearly and it is written black and white on the policy documents to show it is the case. Otherwise, it can get complicated and ugly when you have a claim and they have didn’t know about these cool gadgets you installed. They may actually refuse to pay for them and can even deny the whole claim if they deem that the accident happened because of a thing you have done like changing the engine to a bigger and faster one.