By early 2009 this voluntary program had translated into about 50 hybrid operating on Boston's streets. In August 2008 Boston mandated that all its 1,825 taxi fleet must be converted to hybrids by 2015. As of March 2009 about 10% of the taxicab fleet were already hybrids as owner voluntarily began introducing HEVs since 2002, mainly Toyota Camry Hybrids plus those introduced by the incentives of the CleanAir Cabs. However, in March 2009 a group of taxi drivers and medallion owners sued in federal court the City of Boston to block the requirement and requested the city to delay the changeover for two or three years. They also complained that the new rule is unreasonable because it forbids taxi owners from buying used hybrids. In July 2009 a federal judge granted the request for a temporary injunction and ordered the city to stop enforcing the rule requiring medallion owners to buy new hybrid cars by 2015. Among others, the taxi owners argued that the requirements infringe on federal authority to set fuel-economy and emissions standards, an argument successfully used by New York cab owners to block a similar requirement. In April 2012, the City of Boston awarded the Boston Cab Association with the 2012 Green Business Award for its fleet conversion to hybrid vehicles. Boston Cab has more than 400 hybrid taxis out of its 500 vehicle fleet, and has plans to convert the entire fleet. In April 2008, the city of Cambridge, Massachusetts, in partnership with Whole Foods Market, began its Clear Air Cab program to promote the introduction of hybrid taxis with the objective to reduce the environmental impact of the city's taxicabs by encouraging a switch to hybrid vehicles. Whole Foods made a gift to sponsor the purchase of first six new Toyota Camry Hybrid taxis. In exchange, the company obtained exclusive three-year rights to display advertisements on these taxis. The city of Cambridge provided an additional grant per vehicle, using funds from the auction of two taxi medallions. As of March 2009, the program resulted in 15 hybrid taxis operating in the city. Whole Foods is no longer providing grants but the city continues to do so. The taxis participating in the Clean Air Cab program display a distinctive green stripe   According to the Cambridge License Commission (CLC), and based on a study conducted by John Moore, along with Boston Cab and the Boston Public Health Commission, the average Cambridge cab driver travels about per shift. Assuming a gasoline price of per gallon ($0.79 per liter), the cab drivers would save an average of $18 to $21 per shift. During an average shift a Cambridge hybrid taxi will use between three and four gallons of gasoline as opposed to 10 gallons or more burnt by an outdated Crown Victoria taxicab.