What is the ruling on a merchant who undervalues a commodity, such as a car offered for sale, and what is his punishment in this world and the hereafter?

Unjustifiable loss (Ghabn) is forbidden if it occurs through deception, fraud, lying, or misleading; for it involves misleading the buyer and engaging in prohibited deception. However, if the purchase is made at a low price without deception or coercion, and the owner of the merchandise knows its value and market price and willingly agrees to the sale, then there is no harm in that.