Contact a local auto insurance agent. Ask about the kind of insurance coverage available for the type of work you are doing. Alternately, surf the Internet and find out the name of companies that offer insurance for those who pick up and deliver other people's cars.
Ask for Business Liability Coverage. This should provide comprehensive coverage.
Ask for quotes from different companies to compare general business liability coverage insurance. Compare the premium that is charged by different companies.
Inform the agent or insurance company regarding the nature of your work and business. Tell them that you require liability coverage as you do not own the other people's car.
Get all the details of the suitable policy and ensure that you do not pay too high premium. If you receive very high quotes, then negotiate. Make sure that your insurance company understands that you would be using the car only for a specific purpose.