Avis is buying Zipcar, the largest car-sharing network in the world, a move that will allow the traditional car rental company to tap into the increasingly popular alternative of car sharing. For travelers visiting large metro areas, car sharing offers a less-expensive alternative to renting a car for a full day. The purchase also would allow Avis to better match up with Hertz (HTZ), which has its own car-sharing operation, Hertz on Demand, with offices in the U.S. and Europe. Zipcar and Hertz on Demand park cars across cities, many of which are in reserved parking spaces, and renters can pick them up, then return them, making reservations online or through mobile apps. The cost of fuel and insurance is part of the price, at least for the first 180 miles, unlike traditional rental car companies that charge for gas and insurance coverage separately. (USA Today).