Fast Company The Business of Cars September 2008 is a milestone month for U.S. automakers: General Motors and the Ford Model T both turn 100 years old. We wish they had more to celebrate, but in their honor, here's a look at the business of cars. By Clay Dillow In 1908, a gallon of gas cost around 18 cents. Adjusted for inflation, that's about $3.90. A version of this article appeared in the September 2008 issue of Fast Company magazine.