Based upon its forecasted price drop for li-ion batteries, DB concludes that:
DB's December 2010 study can be read in its entirety by clicking here (PDF). Who wants to guess what DB's outlook will be in late 2011The consumer economics of a pure electric start to work without subsidy by about 2020 under this battery price decline scenario. The industry rule of thumb suggests that consumers will consider a 3-4 year payback to be an economic choice. With no subsidy, 2012 electric vehicle models will have a 10+ year payback vs. a typical combustion analog, assuming $3.25/gallon gasoline. With a $7,500/vehicle subsidy in 2012, an electric will have about a 5 year payback. Around 2015, assuming a $4,500/vehicle subsidy, the payback period starts to fall into a range at which consumers will view the economics favorably. By 2020, the economics should be able to more or less stand on their own with subsidy, and a small subsidy would clearly nudge the payback below 3 years.
[Source: Bio Age (PDF)]