The 2013 Toyota Camry is still America's best-selling car, but its lead is shrinking. Toyota is hinting that changes are coming to its mainstay sedan. Photo credit: Toyota.

Sales of key models can be important indicators of an automaker's earnings health. Midsized sedans are one segment that analysts watch closely, because they're the best-selling cars in the U.S. market. 

For more than a decade, Toyota's (NYSE:TM) Camry has led that segment. The Camry's reputation for reliability and value continue to draw plenty of buyers, but the Camry's sales lead has shrunk this year. Honda's (NYSE:HMC) Accord, Nissan's (NASDAQOTH:NSANY) Altima, and Ford's (NYSE:F) Fusion are all strong new models, and each has made big sales gains in 2013 -- at Toyota's expense.

Toyota's U.S. managers are determined to protect the Camry's lead, and this past week, a Toyota executive dropped strong hints that changes are coming to America's best-selling car. In this video, Fool contributor John Rosevear looks at the sate of this sales race, and at what Toyota might have in mind for its mainstay sedan.