I’m not a car person (their color is about the only thing I notice about cars), so when I need to use a car in my novels, I have to do some work to ascertain which make and model is appropriate and whether or not that particular vehicle would have been available to my character. Was a car like that sold in her region? (A French import might have been available in New York in the Twenties but not in Iowa, for example.) And if it were available, could my character have afforded it? So I’ve looked into the prices of cars. Oddly enough, while the price of almost everything goes up over the decades, the price of cars falls dramatically.
For example, the Ford Model T cost $1200 in 1909. Five years later, it cost $490 (or about $11,000 in today’s money). By 1921, the same car was $310, or roughly $4,000 in today’s money. Why the big drop? The car didn’t change much over those years, but the real savings comes from Ford’s increasing efficiency at his factory. His wanted to produce a car that average Americans could afford, and by the Roaring Twenties, he had. So I was comfortable having my character buy a Ford in 1924–it didn’t cost her all that much.
By the way, it wasn’t Ford but General Motors that introduced the concept of buying cars on credit, with General Motors Acceptance Corporation (GMAC) in 1919. Instead of paying cash, you could finance through GMAC, bypassing the banks. Sales boomed for GM, as by 1926, 75% of all car buyers were using credit to purchase their cars.