Now, almost four years later, I thought it would be interesting to take a look at how the adoption of EVs ( combining PHEVs or plug-in hybrid electric vehicles such as the Chevy Volt and AEVs or all-electric vehicles such as the Nissan Leaf) is progressing in comparison to the very rudimentary model.

I used Ghosn's response to President Obama's call for one million EVs on the road by 2015, i.e., that that number would be "easily surpassed." I assumed two million in 2015 and 230 million in 2050 and used those points as input to the logistic function. I used Wolfram Alpha to plot the data (if you click the link, the assumptions will be built into the input and you can change them to suit). Of course, the plot starts in 2015 and EVs and PHEVs started to be on the road in 2010 and it's now 2013. But nothing stops me from plugging negative numbers into the plot range to go from 2010 to 2015 (or numerically evaluating the function). Doing so predicts (here I assume January 1, 2010 is -5.0 years, January 1, 2015 is 0 years, and here, about 7/12 of the way through 2013, we're at -1.42 years) just over 1.5 million EVs and PHEVs on the road.

What is the actual number? The best data I've found is at the Electric Drive Transportation Association's site. They've compiled it here and the pertinent graph is to the left (click to enbiggen). The astute reader will note that the actual number is about 112,000, less than 10% of my speculative number. With a year and a half to reach 2015, and two and a half to reach the end of 2015, Ghosn's prediction is looking precarious. Let's speculate some more.

What if I plug actual data into a logistic curve (the curve form EDTA certainly doesn't preclude such a model)? I'll use 112,000 in 2013.5 and 230 million for the ultimate number and see what growth rate yields 6,669 (from the graph using GraphClick) in June of 2011. The rate turns out to be 141% annual growth (initially). I doubt that this growth can be sustained indefinitely as early adopters complete adoption and the curve flattens. Such a rate would result in a 230 million EV fleet in around 2022. It's unimaginable that this could take place. Still, if the growth rate continues, we'll have two million EVs on the road sometime in mid 2015.

I used Ghosn's response to President Obama's call for one million EVs on the road by 2015, i.e., that that number would be "easily surpassed." I assumed two million in 2015 and 230 million in 2050 and used those points as input to the logistic function. I used Wolfram Alpha to plot the data (if you click the link, the assumptions will be built into the input and you can change them to suit). Of course, the plot starts in 2015 and EVs and PHEVs started to be on the road in 2010 and it's now 2013. But nothing stops me from plugging negative numbers into the plot range to go from 2010 to 2015 (or numerically evaluating the function). Doing so predicts (here I assume January 1, 2010 is -5.0 years, January 1, 2015 is 0 years, and here, about 7/12 of the way through 2013, we're at -1.42 years) just over 1.5 million EVs and PHEVs on the road.

What is the actual number? The best data I've found is at the Electric Drive Transportation Association's site. They've compiled it here and the pertinent graph is to the left (click to enbiggen). The astute reader will note that the actual number is about 112,000, less than 10% of my speculative number. With a year and a half to reach 2015, and two and a half to reach the end of 2015, Ghosn's prediction is looking precarious. Let's speculate some more.

What if I plug actual data into a logistic curve (the curve form EDTA certainly doesn't preclude such a model)? I'll use 112,000 in 2013.5 and 230 million for the ultimate number and see what growth rate yields 6,669 (from the graph using GraphClick) in June of 2011. The rate turns out to be 141% annual growth (initially). I doubt that this growth can be sustained indefinitely as early adopters complete adoption and the curve flattens. Such a rate would result in a 230 million EV fleet in around 2022. It's unimaginable that this could take place. Still, if the growth rate continues, we'll have two million EVs on the road sometime in mid 2015.

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