The three numbers stand for three key factors that consumers should use to determine how much they can afford to spend on a new car. These refer to a down payment of at least 20%, a financing program that lasts no more than four years (48 months), and a combined insurance and interest cost that is no more than 10% of a household’s gross income. Unsettlingly, consumers aren't adhering to the rule
. Currently, the average cost of a new car or light truck for 2016 in the US is $33,865 by Kelly Blue Book’s count. By that measure, even San Jose, California, the city ranked highest for car affordability, falls short by about $1,000. Buyers there can average an affordable car purchase of $32,856 with a monthly payment of $662.