Few people know that a concept car version of the Prius hybrid was shown at the Tokyo Motor show in 1995. It took two years until the actual Prius launched in Japan, but 2015 marks the 20th anniversary of that original idea that turned into a catalyst for the rest of the industry to start working on the electrification of the traditional drivetrain based on the internal combustion engine.
Toyota has more than an anniversary to celebrate, though. It has also reached a new milestone with the Prius and its various descendants: 8 million cumulative units sold since 1997.
Note the huge jump from 2011 to 2012, and then the plateau. I suspect that the redesigned Prius that came out around that time, along with new models like the smaller Prius C and larger Prius V, helped sales go up rapidly, but then the increased competition from electric cars and plug-in hybrids (Nissan LEAF, Chevrolet Volt, etc) probably made growth slow.
Here's how things break down by model:
You can see that out of the 8 million, 5,264,300 are from the Prius family, or over 65% of the total. The Camry Hybrid is the next most popular hybrid with over half a million.
Toyota calculates that as of July 31, its hybrid vehicles have resulted in approximately 58 million fewer tons of CO2 emissions than would have been emitted by gasoline-powered vehicles of similar size and driving performance. Toyota also estimates that its hybrid vehicles have saved approximately 5.8 billion gallons of gasoline compared to the amount used by gasoline-powered vehicles of similar sizes.
All those unused gallons of gasoline don't just help reduce greenhouse gas emissions. They also have a direct impact on air quality, especially in urban areas. Hybrids generally produce a lot less smog-forming emissions than non-hybrids (they often get the AT-PZEV certification).
The Japanese company isn't done yet either. They've already announced that the RAV4 would get the hybrid treatment for the 2016 model year, and will no doubt keep adding hybrid drivetrains to more models over time.
I wish they would standardize all their hybrids to being plug-in hybrids since this makes quite a difference, especially for short city trips. Even if they don't make the batteries much beefier, just having a few miles that can be driven in electric-only mode from power that came from the grid rather than the gasoline engine would be nice.