When Zipcar first launched in Cambridge, Mass., in 2000, smart phones hadn't been invented and social media sites didn't exist. Today, Zipcar vehicles are parked in reserved spots in more than 470 cities and towns and on more than 400 college campuses worldwide, according to the company.

To celebrate its birthday, Zipcar is planning to host promotions, events and parties in communities and cities around the world throughout 2015.

Zipcar has grown from its first car — a VW Bug named Bilbo, which was accessed via a key hidden under a rock — to a technologically-advanced international business. With a variety of service options and more than 30 vehicle types from which to choose, Zipcar continues to drive growth in its car-sharing network, says the company.

Over the next 15 years, Zipcar will continue to bring car sharing to more people in more places around the world, including in the Europe, the Middle East and Asia-Pacific regions.

"Zipcar has grown from a small startup to become an international, profitable mainstream business that is having a demonstrable impact on cities around the world," said Zipcar President Kaye Ceille. "We are proud to have paved the way for other innovations in urban transportation and are pleased to see the transformation under way in urban mobility as more and more people turn to access versus ownership. We're getting closer to our vision of a world where car sharers outnumber car owners every day, and that's fulfilling."

According to Zipcar, here are some stats on its services:

• A single Zipcar can support the driving needs of about 40 members.

• Zipcar members report saving up to $600 per month compared to owning a car, money that is often put back into local businesses, restaurants and entertainment.

• More than 1.3 billion miles have been driven by Zipcar members in 15 years — that's the equivalent of a trip past Saturn.

• A Zipcar is reserved every six seconds.

• Zipcar's most popular pod is in the neighborhood around Northeastern University in Boston, with more than 64,500 reservations since cars were first added to the location.

• In the past 15 years, Zipcar has offered nearly 250 different car models, including hybrids, electric vehicles, SUVs, minivans, cargo vans and luxury vehicles.