Polly and Penelope should consider forming a limited liability company (LLC) or a corporation for their car dealership. These business structures provide personal liability protection for the owners, meaning they are typically not personally responsible for the company's debts and liabilities.
By establishing an LLC or corporation, Polly and Penelope would protect their personal assets from being at risk in the event that the dealership encounters financial difficulties or goes out of business. It's advisable for them to consult with a legal or financial professional to understand the best structure for their specific situation and to ensure all necessary legal steps are followed.