Which fact must be disclosed in dealer-to-dealer sales and leases regarding a vehicle's history?

In dealer-to-dealer sales and leases, disclosing any accidents involving the vehicle is crucial because it directly impacts the vehicle's history and potentially its value and safety. Knowledge of past accidents allows dealers to make informed decisions about purchasing or selling a vehicle, and it enables them to present accurate information to potential customers. This transparency is essential in maintaining trust and ethical practices within the automotive industry.

While the other options, such as fuel efficiency ratings, previous number of owners, and warranty status, provide useful information, they do not carry the same weight in terms of legal and ethical obligations as accident history. Accident disclosures address significant concerns regarding a vehicle's condition and operational safety, which are vital factors for dealers and future buyers.