Year 2015 has been worse than 2014 in terms of plug-in electric car sales.

Through the end of July, monthly sales were averaging 9,043 units, some 600 (or over 6%) less than in the first seven months of 2014.
It’s not clear whether the second half of the year will reverse the totals and by how much, although the mid-term perspective seems very optimistic because:
next generation 2016 Chevrolet Volt
expected improved 2016 Nissan LEAF with larger battery pack and range
Tesla Model X ramp-up
new entry-level Volkswagen e-Golf priced under 30k
new entry Audi A3 Sportback e-tron from $37,900
more models will be flooding the market in the FAll like recent Mercedes S550 PHV and C350e, Volvo XC90, etc.
We expect the EV sales turn-around to beginning in September, and to really gain significant momentum in October before following through strong for the entire 2016 sales season.