Which practice is advisable when making promises during a vehicle sale?

When making promises during a vehicle sale, it is advisable that those promises be documented in writing. This is because written promises provide a clear and concrete reference for both the seller and the buyer. Written agreements help to prevent misunderstandings and disputes later on, as they outline the specific terms of the promise made.

By having a written document, both parties can refer back to it if there are any issues regarding what was promised, thus making it easier to resolve potential disagreements. The clarity provided by written terms also reinforces trust in the transaction, as it demonstrates the seller's commitment to honoring the promises made.

The other options, while they may have some merit in certain contexts, do not offer the same level of accountability and protection that a written promise does. Relying solely on verbal agreements can lead to confusion and miscommunication, and being vague in promises could jeopardize the transaction's integrity. Providing information about potential risks is important for transparency, but it does not replace the necessity of having promises clearly documented.