Image Source: Mike Lee
Dear Pablo: We're a San Francisco-based cab company and we use hybrids exclusively. In trying to decide between buying Toyota Prius or Ford Fusion cars, some of our company members want the comfort and luxury of the Fusion over the great gas mileage of the Prius. Is the Prius really that much better, in terms of carbon footprint and fuel efficiency, to justify giving up some amenities?
Ultimately the answer to this question depends on the values that an individual brings to the decision. We all place different importance on climate protection, economics, and comfort. Ultimately we need to reconcile the quantifiable and the intangible ourselves. First, let us look at the quantifiable; let us figure out the environmental impact of making and operating both vehicles in question. Then we can overlay the question of amenities, public perception and any other qualitative criteria.What Is The Impact Of Making a Ford Fusion?
The Argonne National Lab has done a great job in analyzing the material intensity and energy consumption in manufacturing vehicles and vehicle fuels. Their work is packaged in the GREET models. According to the assumptions in their model for the average conventional internal combustion engine vehicle (ICEV) it takes 100 million BTU to make the vehicle, batteries, and fluids in an average 3,201 pound vehicle (from Wikipedia: 1 BTU is approximately the amount of energy needed to heat 1 pound of water by 1° F). This comes out to 31,362 BTU/lb. The obvious lesson in this is that heavier vehicles require more energy to make than lighter ones, in general. A Ford Fusion has a curb weight of 3,720 lbs, so its manufacture used roughly 116.6 million BTU (mmbtu).
What Is The Impact Of Making a Toyota Prius?
There has been a study circulating that states that hybrids are more environmentally damaging than Hummers because of the battery production but this has been widely disputed. According to the GREET model a Hybrid Electric Vehicle (HEV) that weighs 2,632 pounds requires 102 million BTU to make, or 38,650 BTU/lb. This small difference in production energy becomes negligible when you factor in the increased fuel efficiency. The Toyota Prius has a curb weight of 3,042 lbs, so its manufacture used roughly 117.6 million BTU (mmbtu), a negligible difference from the heavier, but non-hybrid Ford Fusion.
What Is The Impact Of Operating These Cars?
Gasoline contains 113,500 BTU per gallon so the manufacture of the average car is roughly equivalent to 880 gallons of gasoline. The manufacture of the Prius and the Fusion require the equivalent of about 1000 gallons of gasoline. Various sources estimate the annual mileage of a taxi between 50,000 and 100,000 miles. Assuming 75,000 miles per year, the Prius would use about 1,500 gallons and the the Fusion would use 2,273 gallons of gasoline per year. This difference alone justifies the slightly higher cost of the Prius from an economic and environmental perspective.
The Ford Fusion is also available as a hybrid. Unfortunately it costs at least $10,000 more, putting it on par with the Prius, while only getting a fuel economy of 41/36 (city/highway) mpg, compared to 51/48 mpg. When it comes to comfort, the Fusion has one inch more legroom and two inches more shoulder/hip room for the back seat, while both have virtually the same headroom. If a driver is set on the interior styling or the exterior look of the Ford it may be difficult to convince them otherwise. One argument that can be made is that the customer comes first and, in San Francisco and a growing number of cities, customers are more and more concerned about the environment.
If the economic advantages of the Prius taxi don't make the case, the fact that customers will appreciate the leadership being shown by forward-thinking cabbies should.
Pablo Päster is a weekly columnist for TreeHugger.com and Principal Environmental Consultant at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
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