Behind the wheel in an empty spot of his Cherry Hill law firm's parking lot, Peter Spirgel grinned wickedly. Then he floored it.

Whooah! The Tesla sedan - a Model S Performance, for those who attend to such details - shot from a standstill.

Just eight days into ownership, Spirgel was still like a giddy kid, noting the luxury details, the 17-inch screen that governs everything - "like driving an iPad" a friend said - and, not least, the engineering marvel of a top-end electric car.

When Spirgel took delivery, he became another statistic, albeit a snazzy one, in the growing electric-vehicle marketplace.

Throughout the nation, and the region, cars that get their fuel from a plug, not a nozzle, are making inroads.

Two years into electric vehicles being broadly sold to consumers - notably, through the Chevy Volt and the Nissan Leaf - they remain a fraction of the nation's passenger fleet, due partly to cost.

But nationwide, more than 40,000 plug-in electric vehicles have been sold in the last two years, and in one year, sales tripled. The vehicles are seen as key to meeting the new fuel-efficiency standards of 54.5 miles per gallon by model year 2025.

Electric vehicles are catching stares in parking lots and thumbs-up on highways. Charging stations are burgeoning, too.

The PhillyCarShare program has 21 Volts in 10 locations, and they're becoming a car of choice.

So far, the Volt, which goes 40 miles on a charge before switching to gasoline, is outselling the Nissan Leaf, which is all-electric and gets about 100 miles to a charge.

"I think people are afflicted with range anxiety," said Tom Saxton, vice president of the advocacy group Plug-In America. He defines it as "the irrational fear of running out of charge" before reaching one's destination.

But do the math, Saxton said, and you'll be OK.

The East Coast lags behind the West Coast - partly, researchers say, because there are fewer high-occupancy-vehicle lanes. Restricted to carpoolers and, more recently, hybrid or electric vehicles, they offer a dodge around congested traffic.

But the numbers keep adding up. By mid-April, the 2.2 million passenger cars in the five counties of Southeastern Pennsylvania included 18,700 hybrids and plug-ins.

Since 2011, Pennsylvania has given rebates - most were $3,500 - to 99 electric vehicles and more than 300 plug-in hybrids.

While that program is now closed, New Jersey still gives a sales-tax exemption, and the feds give a tax credit. N.J. officials have tracked an infusion of 735 plug-in electric vehicles through model year 2011. "We're definitely seeing a huge trend in interest," said assistant commissioner Bob Marshall of the Department of Environmental Protection.

One reason New Jersey officials value electric cars is that, unlike coal-dominated Pennsylvania, cleaner nuclear power accounts for about half of the state's energy output.

While electric cars have no tailpipe emissions, the electricity source is part of the green equation.

This also means that transportation makes up the bulk of the state's ozone pollution, which officials would love to see reduced.

With a $388,000 federal grant and many partners, the Delaware Valley Regional Planning Commission has been studying the Southeastern Pennsylvania population to see where early EV adoption might occur.

"The question is to figure out how to overcome barriers," said Rob Graff, manager of the commission's office of energy and climate change initiatives.

Factoring in income, population density, and other details, the commission cited these as prime areas: Solebury, Radnor, Abington/Jenkintown, Easttown/Tredyffrin, Lower Merion, Swarthmore, Media, Old City.

But barriers remain, including familiarity with the technology.

Plus, of course, the cost. Base price for the Leaf is $27,700; for the Volt, it's $31,600. Both totals are after the $7,500 federal tax credit.

(Charging changes the equation. A charging company executive said that, nationwide, gasoline costs 16 to 18 cents a mile vs. two to three cents a mile for electricity.)

So while Philadelphia has strong goals for reducing vehicle emissions, officials are squeamish about putting public money into a technology that, for now, only the rich can afford.

But they are happy to encourage adoption by, say, smoothing out building codes and inspections for charging stations.

Spirgel, CEO of the Flaster/Greenberg law firm, is happy to play the role of early adopter. "Someone has to start this transition. And if people start driving these, the batteries will get better, they'll get a longer range, they'll get cheaper."

He did have the means to buy a model that starts at about $80,000 and has a 300-mile range.

But he didn't want something that looked like "a granola car." His kids, now grown, think it's the first cool car he has ever driven.

Meanwhile, research agencies are in data-collection overdrive.

Data are considered so vital to predicting what might happen that one national firm, ECOtality, gives free household chargers for Leaf and Volt buyers in exchange for data. Its EV Project is a $120 million partnership with the U.S. Department of Energy to gather information on how electric vehicles are being used.

So far, ECOtality also has installed 21 commercial charging stations in the region, often with fanfare. At Temple University, they welcomed the new chargers with a group dance of the electric slide.

It's too soon for local conclusions, but nationally, researchers have found that when chargers are installed at retail locations, electric-car drivers visit two to three times more often than the outlet's most loyal customers, and they stay for longer periods.

This could make recharging "part of everyday life," said ECOtality's Colin Read.

Chargers seem to be popping up all over - at the Pennsylvania Horticultural Society, the Convention Center parking garage, the King of Prussia Mall (bringing new meaning to the phrase "charge it").

Pennsylvania Turnpike drivers, come summer, will begin seeing them at rest stops.

Like a growing number of businesses, Spirgel's firm has installed stations, free for clients and employees. New Jersey now has at least 82 public and private stations.

But use has been spotty. The best that Norman Zarwin, chairman of the charging company U-Go, can say is that "it's gradual." But he and his partners are in it for the long term, not expecting profit for four or five years.

Zarwin, 82, said he did it for posterity and because it was "clear where the future should be."

Other infrastructure is in the works. OnStar, GM's safety, navigation, and communication arm, is developing apps to help electric-vehicle drivers calculate their range, find charging stations, and tap their phones to a charging device to start the juice.

Of course, electric cars could be overtaken by other technologies.

But after a ride in Spirgel's Tesla, Frank Riesenburger, chairman of the firm's environmental practice group, was grinning.

"This is absolutely the future of where automobiles are going to go," he said. "How long the infrastructure is going to take to build, we don't know. But it's here."

Spirgel's Tesla is about to get greener still. He's putting solar panels on his home's roof to charge it.