The measurement of which is the greenest taxi company usually comes down to how many hybrids are in its fleet. Metro Taxi in Denver is going there and much further by squeezing every last ounce of energy from its fossil fuels.

According to the company, Metro Taxi will save 2.6 million gallons of gasoline annually  or an estimated 5090 gallons per car by replacing their 500 taxis with a fleet of Toyota Prius cars.

Other taxi companies in major green-minded metropolitan areas are replacing their fleets with hybrids and natural gas vehicles such as San Francisco Green Cab. In fact, San Francisco Mayor Gavin Newsom signed new legislation making it easier for taxi companies to purchase green vehicles in 2006.

But, there is more to going green than purchasing hybrids. Metro Taxi, for example, is greening their entire operations. Their building is powered by two Clean Burn furnaces, which take used oil from their vehicles and burning it through specially manufactured furnaces. The byproduct of that process is heat available to warm Metro Taxi offices. This process recovers built-in energy for heating and eliminates used oil that could end up in a landfill.

Moving to green fleets prevents continued contributions to air pollution and greenhouse gas emissions, and it indirectly reduces the heat island effect by not contributing smog-forming pollutants to the air.

From a monetary perspective, green fleets make cents. Companies can take advantage of tax breaks, save money on operation costs like gasoline, and recoup revenue that is now lost with the reduction of travel.

I’ll take a green cab which is considerably newer than the 1990 generation of cabs I ride in to and from the San Francisco airport any day. Going green increases customer satisfaction.

 Greening both a company’s direct (vehicles in this case) and indirect operations (management offices), is the eco-conscious progression of greening that company. What can companies do to be a greener shade of green?

A taxi company can purchase carbon offsets, or power their office with solar energy. Maybe they should consider car-sharing: load two people into a cab from the airport instead of one.

While green washing is prevalent and companies tout “all-natural” and other lingo, a company truly engaged in environmental preservation and in growing sustainably, is greening all parts of their business and doing so legitimately. This is an important business axiom: without growing sustainably, the impact on the environment could eliminate opportunities to make a profit.