Earlier this year, Kenneth and Lorryn Calicchio bought a 2015 Volkswagen Jetta from Toms River Volkswagen, thinking its diesel engine met federal air quality standards. But the couple learned that VW engineers had installed software that activated pollution controls only during emissions tests.

The rest of the time, the car emitted as much as 40 times the pollutants permitted under federal clean air standards.

So much for their dream of owning an eco-friendly car.

Now the Calicchios have joined thousands of other VW owners in filing about 300 proposed class-action lawsuits nationwide, alleging they were tricked into buying cars the company said were good for the environment but instead spewed pollutants. They say their cars are worth far less than what they paid for them, and there is evidence to back up that claim.

The market value of affected vehicles has fallen an average of 13 percent, or about $1,700 per vehicle, since mid-September as car dealers stay away from the tainted vehicles, according to used-car pricing guide Kelley Blue Book.

VW acknowledged in September that its engineers had installed a "defeat device" in about 500,000 VW Jettas, Beetles, Passats, and other vehicles. EPA officials subsequently found that software designed to activate pollution controls only during emissions tests, and deactivating the controls during normal driving, also had been installed on some Audi and Porsche models, both VW subsidiaries.

Worldwide, the number of cars with rigged pollution controls is expected to reach 11 million.

Across the country, thousands of outraged car owners are alleging misdeeds by Volkswagen AG. Among the law firms in the Philadelphia area that are involved in the litigation are Berger & Montague and Locks Law Firm, both of Center City.

Key court decisions are expected in December and early January, when a panel of federal judges is expected to decide where the cases will be consolidated and tried, while also selecting a judge to hear the matter. California, New Jersey, and Michigan are said to be at the top of the list for where the consolidated case will be heard. New Jersey is considered a top contender because, among potential jurisdictions, it is among the closest to Germany, where the company's global headquarters are located. VW is asking that the case be heard in Detroit, while California is high on the list because the state's stringent air pollution rules were breached.

Ease of travel to the United States by VW executives, who likely will be deposed, and access to company documents are among the factors weighing in favor of New Jersey, legal experts say.

After a panel of federal judges likely consolidates the cases in one court and selects a judge to oversee the case, "relatively shortly thereafter the judge will pick leadership for the case among the plaintiffs' [lawyers]," said Sherrie R. Savett of the Berger & Montague firm. Berger & Montague is one of the nation's leading class-action law firms, and has filed a suit against VW in New Jersey.

The firm's complaint is illustrative of the argument that many plaintiffs' lawyers are making - that VW owners paid a premium of as much as 31 percent for diesel engines they thought were good for the environment while delivering superior performance. But they suffered economic harm to the tune of thousands of dollars per car because the cars were not what VW said they were.

The complaint also alleges that any fix to the emissions problem likely will cause the cars' performance to suffer.

"Not only did class members pay too much for cars now worth substantially less, but they will end up paying more in fuel for their less efficient cars over the years they own their vehicles," according to the complaint.

While the lawyers suing VW won't have to work hard to prove that the company engaged in deceptive tactics, the more challenging task may be obtaining what is known in law as class certification. That is a key hurdle, because it permits lawyers to make claims on behalf of thousands of people in one lawsuit, rather than trying the cases separately. For a class to be certified, a judge must determine that the harm suffered by the plaintiffs is substantially similar and that the same remedy can reasonably apply across the class.

While most lawyers anticipate the VW plaintiffs will be certified as a class, Steve Berman, name partner at the Seattle-based class-action law firm Hagens Berman, said the types of economic harm that owners might be able to claim are so disparate, it is possible a judge may conclude there are not enough similarities.

In the end, however, Berman, who has served as lead counsel in several prominent class actions, including the tobacco litigation of the late 1990s, said he thought the class would be certified.