X Wished to Purchase a Motor Vehicle from Y on Credit

True/False

X wished to purchase a motor vehicle from Y on credit, but X was unemployed, and Y was hesitant to sell to him for that reason. Z, who was quite wealthy, said to Y: "Sell X the automobile on credit, and if X does not pay you, I will." Z's promise would be unenforceable, unless it was made in writing and signed by Z.