A tank of gas

While waiting at a car repair shop I heard a four year old little boy ask his mom if they were still going to make it to Grandmas house for Christmas.She tried to explain to him that if the car repair cost too much they might not have money for the gas. As the repair man returned to inform her the repairs would be more than expected, the boy replied " mister if we pay for the repairs will you fill up our gas tank with your money so we can go to Grandma's?" As they were leaving he handed them a gas card signed love from Grandma.