The car rental market is one of the markets that are constantly getting greener, offering a growing number of green services from the newest electric cars to car sharing programs. Yet surprisingly, none of the major car rental companies, until now, have published a sustainability report. Well, that was true until last week when Enterprise Holdings (which owns and operates the Alamo, Enterprise Rent-A-Car and National Car brands) took the lead and announced the release of its first ever sustainability report.