The first hybrid vehicle introduced to the United States debuted 22 years ago - the Honda Insight. The following year, the Toyota Prius entered the market and the hybrid market began to accelerate quickly. By 2007, sales eclipsed 350,000 units from just 13 models, and some were predicting that more than 100 hybrid models would soon be available for sale in the U.S. Those forecasts were never realized and year after year sales hovered at or below 3%, setting a record of 3.2% of sales in 2013 before slipping to less than 2% just three years later. But recent data indicates that automobile manufacturers may not have given up on this technology, and in the first quarter of 2021 hybrids clawed up to 4.5% of sales. What has changed and what can we learn from the experience of hybrid vehicles?