Electric vehicles (EVs) are an emerging market in California and present an opportunity for emissions reductions in the transportation sector. In order for the EV market to grow, however, it is important to discern which factors affect the EV sales. Ding (2017) used demand theory to create a model to prove that if the cost of conventional vehicles are high, then the demand for energy efficient vehicles will increase. Ding (2017) examined EV sales across the entire United States, and found that retail gasoline prices and residential electricity prices may affect the sales of EVs. This study narrows the focus to California, assessing whether retail gasoline prices, residential electricity prices and a new independent variable, the percentage of renewable resources used in the electricity generation mix, affect plug-in hybrid electric vehicle (PHEV) and battery electric vehicle (BEV) sales in the state. The results of the Robust Regression demonstrate that a decrease in gasoline price leads to an increase in both PHEV and BEV sales, while an increase in residential electricity price leads to an increase in the sales of these vehicles. Also, an increase in the percentage of renewable resources used in the electricity generation mix leads to an increase in PHEV and BEV sales. Certain results are unexpected, but make sense when EV market conditions specific to California are considered.