Three wheelin'

ZAP cars produce zero emissions and cost just pennies per mile to run. So why are they illegal in Massachusetts?

ZAP's Xebra Xero sedan, shown in Zebra Flash paint, starts at $11,700. (ZAP)

With gas prices so high, surely you've heard of the ZAP car?

No, not a Zipcar, which urbanites rent by the hour for quick trips around town.

A ZAP car, as in the 2008 ZAP Xebra Sedan, an electric vehicle with three wheels - two in the back, and one centered in the front - seats four people with a maximum combined weight of 500 pounds, has zero emissions, and at $11,700, carries a reasonable price tag for a green machine.

Drawing a blank? Well, you're not alone, because in Massachusetts, ZAP cars aren't allowed on the road. In fact, they're illegal.

An electric car that's against the law might seem like an oxymoron these days. But the ZAP car is hardly the most conventional vehicle on the market. Indeed, it's so odd that the Massachusetts Registry of Motor Vehicles has just formed a task force to write the state's first legal definition for a host of unusual gas-saving contraptions that are suddenly viable alternatives to cars, trucks, and SUVs.

Even more eye-opening, the ZAP car - of which just under 1,000 have been sold in the United States, and just four in Massachusetts - could be responsible for a statewide initiative within the next year that would post thousands of "minimum speed" signs on highways and state-numbered roadways.

That's minimum - as in, you have to speed up.

"There's a possibility of that," said Ann Dufresne, Registry spokeswoman.

All this for a vehicle the Wall Street Journal called a Tic Tac on wheels because of its capsule shape? I'll try to explain.

The ZAP Xebra's dimensions are similar to those of a Smart Car (the Xebra is a foot longer, while the Smart Car is a half foot wider), making it ideal for puny city parking spaces and narrow, congested streets. But the Chinese-made Xebra runs on electricity, not gas, averaging 25 miles per six-hour charge. You plug it into a standard outlet, as you would any appliance. (Alas for apartment dwellers, that might require running an extension cord out the window.) It produces no harmful emissions (ZAP, the U.S. distributor's name, stands for "Zero Air Pollution"), and since it doesn't burn fuel, it's far cheaper to operate than whatever's in your driveway.

Company spokesman Alex Campbell told me that it takes about 4.5 kilowatt hours of electricity to recharge his Xebra Sedan (ZAP also distributes a miniature pick-up truck version. Check it out at www.zapworld.com.)

According to my last electric bill, I paid about 23 cents per kilowatt hour, which means I'd spend less than $1 for 25 miles of travel if I owned a ZAP car.

The Registry doesn't have any issues with what I've told you so far. The rub with Xebras, said Dufresne, is that while they may look like small cars, the federal government classifies them as motorcycles because they have fewer than four wheels. More than 40 states have accepted that classification, according to ZAP, but not Massachusetts.

For one thing, Dufresne said, Massachusetts laws clearly state that a vehicle can't be a motorcycle if "the operator and passenger ride within an enclosed cab." You sit inside a ZAP car, so it fails that test.

But even if the Registry were to make an exception, allowing ZAP cars on the road as "motorcycles" invites a set of problems, Dufresne said. Each owner would need a special motorcycle driver's license and would need to abide by the state's helmet law, wearing one inside the car. (Passengers would, too.)

Xebras have a maximum speed of 40 miles per hour, but if they are classified as motorcycles (or cars, for that matter), drivers could ride them anywhere. That means they could be driven on major highways where traffic is moving at 55 or faster. No matter what vehicle you're in, driving 20 or 30 miles per hour slower than everyone else is dangerous.

ZAP cars aren't tested for crash impacts as a standard car would be because of their federal designation as motorcycles. But since the driver sits in an enclosed cabin, he or she might have a false sense of security, Dufresne said.

"We're concerned about drivers' safety," she said.

ZAP officials, however, question our state's reaction to their vehicles, saying their cars work just fine in states known for highway driving, such as California, because people are wise enough not to take them on the freeway. Other states forbid the practice.

"We do not recommend people going on the highway. It's a 40 mile-per-hour vehicle," Campbell said. "I drive my Xebra almost exclusively on city streets. If I do go on a highway, it's just real brief."

Doug Hart, a Boston investment adviser, was the first Massachusetts resident to purchase a ZAP car two years ago. He said he didn't have a single problem running errands with it in his hometown of Duxbury before the Registry took a stand against ZAP cars in July and revoked his registration (improperly issued, the Registry told him).

"I wasn't driving my other car, so I saved gas and I was making a good statement about the environment," Hart said.

Chances are, however, that Hart will be back on the road sometime next year. State Senator Robert Hedlund, a Weymouth Republican, and state Representative Garrett Bradley, a Hingham Democrat, filed a bill this summer aimed at legalizing Xebras and other "medium-speed" electric vehicles on roads with speed limits of 40 miles per hour or less. Other legislation, filed by House Republican leader Bradley Jones of North Reading, would restrict any low-speed vehicle, gas or electric, to local roads.

"We'd like to think we're so enlightened in this state on technology matters," Hedlund said, "but we are way behind the country on this."

"There are times we need our SUV for our family - for weekend trips where we have to lug stuff around like kayaks or something. But all I need is basically a one-seater that gets me to work," said David Ting, a Massachusetts General Hospital doctor who's considering buying one.

"I live in Lexington. I take the back roads to Boston," he said. "For me, a vehicle with a range of 20 miles would be just about right."

All Ting wants, he said, is for the state to tell him it will be legal.

Peter DeMarco can be reached at demarco@globe.com.