Selling discount coupons for gas

We are offering a program to sell fuel to people, the details of which are as follows: pay 200 riyaals and get coupons for gas worth 210 riyaals plus a free car wash, knowing that the amount of 200 riyaals is being paid in advance when you buy the gas coupons. Is this offer halaal or haraam?

Praise be to Allah, and blessings and peace be upon the Messenger of Allah:

If the matter is as described, it is permissible to sell the coupons for gas plus a car wash for the amount stated, because the sale is in fact for the amount of gas described plus the car wash, and there is no deception, ribaa or jahaalah (purchase of unknown product) involved.