For each taxi boosted to just 22 mpg—the average vehicle on the road, roughly—the climate would be spared about 570 gallons of gas and more than 7 tons of carbon-dioxide.* It’d be like taking a car off the road for good. It’d be like upgrading an average car to one that gets 140 mpg. It’d be groovy.
The city of Seattle regulates the taxi medallions. So one good step would be to provide strong incentives to switch to cleaner and more efficient vehicles. Requiring hybrid taxis—which are in use in New York City and Vancouver—might be in order.
Hybrid taxis, by the way, are rated at 36 mpg in the city. So the savings could be more like 800+ gallons of gas and over 10 tons of carbon-dioxide saved.* Multiply that by the 667 cabs in Seattle’s fleet and it’s starting to look like a serious climate benefit.
*My figures are probably ridiculously conservative because they’re computed on the basis of 15,000 miles driven per year. Cabs almost certainly drive far more than that. In fact, the city’s report appears to be using higher numbers. The report, however, doesn’t make clear whether it’s just some cabs that get 12 mpg or if that’s the fleet average.