The Low Carbon Vehicle Partnership (LowCVP) says that by 2030, the total ownership cost differential for advanced-technology automobiles will drop to £2,400 ($3,825 U.S. at the current exchange rate) for plug-in hybrid electric vehicles and dip to £3,000 ($4,782 U.S.) for electric-only vehicles, compared to conventional internal combustion engine (ICE) vehicles. In 2010, this cost differential was closer to £20,000 ($31,954 U.S.) for pure electrics, excluding incentives and automaker discounts, says LowCVP.
The study, based on assumptions of the situation in the UK, concludes that as ICE vehicles continue to increase in efficiency, fuel costs contribute to less a portion of total ownership costs. LowCVP says the fuel contribution to ownership costs in 2010 averaged 16 percent, but that this is likely to drop to nine percent by 2030.
There is more data available in this PDF, but here's LowCVP's conclusion: low-carbon vehicles will continue to require significant financial support in the form of incentives if they are ever to become widely adopted. For at least two decades. In the UK. They think.