It's a Mad, Mad, Mad, Mad World 1963

Cars are speeding down the highway toward Las Vegas. In the first car is a businessman with his wife and mother-in-law. In the second is a dentist with his wife. In the third is a pair of friends. They don’t know each other and would likely never have met otherwise. They all witness an accident, and the sole victim reveals a secret to them before he dies: he has hidden a treasure under the Big W. And so the travelers turn into pirates—now they race each other for the treasure, trying their hardest to ruin their rivals’ lives along the way.