Photos: Toyota Prius through the years

Toyota unveils the latest version of the Prius at an event Tuesday, Sept. 8, 2015, in Las Vegas.

(John Locher / AP)

Sept. 8, 2015 9:15 PM PT

The Prius is introduced in Japan in 1997.

(Tsugufumi Matsumoto / Associated Press)

Cumulative Prius sales in the U.S. crossed 1 million vehicles in 2011.

(Irfan Khan / Los Angeles Times)