Sales of plug-in vehicles started from nothing a few years ago and are now at 0.5 percent of the U.S. market roughly, and things are due to heat up.

Year over year sales has seen significant growth, and Pike Research forecasts that in the next seven years plug-in vehicle (PEV) sales will reach 1.8 million units in 102 of the largest U.S. cities. Pike defines a large city as having 500,000 or more residents.

“More than a quarter of all annual U.S. PEV sales will be in the top five metropolitan areas for PEV sales – New York, Los Angeles, San Francisco, Seattle, and Portland,” says Pike’s Senior Research Analyst Dave Hurst. “But thanks to a combination of positive attitudes towards green driving, high fuel prices, and state government support, California metropolitan statistical areas will account for more than one in five PEVs sold.”

Industry forecasting is sometimes akin to fortune telling. However, resolute and positive attitudes by industry leaders toward EVs, like General Motors’ Mark Reuss saying the “electric car is not dead,” and the eventual lowering of comparatively high MSRPs for EVs, as illustrated by Nissan’s recent announcement of a significant price drop for its base model 2013 Leaf, hint at the possibility of Pike’s projections being close to, if not altogether, on target.

Increased U.S.-based production of EVs, as Nissan is doing with the Leaf in Tennessee and is rumored to happen with Toyota’s segment-dominating Prius, along with the proliferation of PEV models from many automakers, could also bolster PEV sales enough to see Pike’s numbers become reality by the end of the decade.

But as Pike indicates, PEV sales likely won’t be self-sustaining, and instead will have help from infrastructure that’s needed to boost consumer confidence in the infant segment.

For example, increasing positive opinions toward PEVs in Texas moved the state’s ranking from 42nd in 2010 to fourth in 2012, the largest change of any state, in a survey by Pike. The research firm attributes the accessibility of charging infrastructure as responsible – at least partially ­– for the leap in Texans’ favorable view of PEVs.