Is it permissible to accept a car as a prize from a lottery draw based on tickets given to distributors of children's diapers, in exchange for purchasing a certain quantity of the product?

If the distributors buy the packages with the intention of benefiting from the profits of selling and distributing them, not with the intention of obtaining the prize, then there is no harm in that. And it is permissible for whoever wins the prize to take it and benefit from it, because it is a permissible incentive. However, if their intention in buying is to obtain the prize, then that is considered forbidden gambling.