Increased safety, more complex infotainment systems, higher quality materials - they all add to the complexity of modern vehicles, which in turn increases their costs. Nobody asked us whether we wanted all this, but since we continued to buy them, the manufacturers simply assumed.And it worked - at least so far. We even managed to go through a financial crisis without too many casualties in the automotive department, and now the market is on a high. And yet a new study by Bankrate (via AutoGuide ) discovered that a U.S. median-income household can only afford the average-priced new car in one of the 25 largest metropolitan areas.The research is based on the '20/4/10' rule, which states that when buying a car you should make a 20 percent down payment, make a loan no longer than four years and aim to spend a maximum of ten percent out of the annual income on payments, interest, and insurance.Bankrate then calculated the average price for the new cars sold in the U.S. in May 2017 and came up with $33,300. It then corroborated data on local sales tax and household incomes to come up with each city's affordable price using the 20/4/10 rule.The results showed that the affordable price was higher than the average one in just one metropolitan area - Washington DC ($37,223.41). All the others fell below it, meaning most American households with an average income can't afford to buy an average-priced new car. And if this is the situation in the U.S., you can only imagine what it's like in other parts of the world.The second on the list was San Francisco, California, with Boston and Seattle following closely. Way down at the bottom sits Miami, Florida , where the affordable price has been calculated at $13,576.83, almost a full $20,000 under the average cost of a new car.