Self-serve car rental company Zipcar is becoming an international enterprise. But that can have its drawbacks, as can be seen by a federal lawsuit filed against the company for allegedly charging customers excessive or hidden fees, according to the Boston Globe.

Illinois resident Ryan Blay filed the lawsuit along with other customers who were potentially charged the fees. The suit was filed in a Boston federal court against Zipcar, which rents vehicles by the hour and by the day from lots and garages scattered around Greater Boston and other cities.

The complaint is also a reminder that Zipcar is now big enough to attract a federal lawsuit by plaintiffs who seek to make it a class-action proceeding. One Boston attorney even called the suit “a backhanded compliment” to Zipcar.

A Zipcar spokeswoman declined to comment on the suit, which stated that many customers may not even be aware of the charges because Zipcar does not send monthly statements.

The suit says the charges are “arbitrary and capricious’’ and disproportionate to the company’s actual costs. For example, the suit contends, customers must pay a $3.50 charge to talk to a customer service representative even when customers call to report a problem that can’t be handled through the Web site or automated phone system. In addition, the suit alleges that customers who receive a parking ticket or traffic citation are typically charged for the cost of the ticket plus an additional fee, even when the ticket was issued in error and customers were not given any opportunity to appeal.

Other accusations in the suit are that Zipcar charges a $50 per hour late fee, a $20 inactivity fee per month if the customer has not used the service for 12 consecutive months, and a charge to retrieve an item left in the vehicle.

The outcome of this suit will probably depend on how clearly Zipcar disclosed the fees, said one lawyer who focuses on commercial litigation.