About a year ago, we rated different versions of the Honda Civic, a compact car that has long been a benchmark for the segment. We looked at the Model Year 2011 versions of the 2011 Honda Civic EX and the Civic Hybrid as well as the Civic GX, which runs on compressed natural gas (CNG). At that time, the GX edged out the hybrid in its AutoEcoRating score, but with new data on pollution during natural gas production, the Civic Hybrid now comes out on top.
As long as it’s been on the market, Honda’s Civic GX had racked up numerous accolades, topping the rankings in ACEEE’s Green Book for many years running. It also earned this year’s Green Car of the Year award, presented by the Green Car Journal.
There’s no doubt that Honda’s engineers have delivered an exemplary design in the Civic GX, making the best of the super-clean combustion possible with natural gas. But Honda can’t control where the natural gas comes from or how cleanly it is produced. After all, natural gas is fossil gas. It’s no more or less “natural” than natural oil and natural coal, all fossil endowments from solar energy accumulated by diatoms, plants and other organisms that lived eons ago.
It turns out that CNG isn’t nearly as clean as had been assumed. EPA and other agencies recently updated the data on pollution from natural gas production and distribution, and we use the new government estimates in our updated version of AutoEcoRating. With the older data, natural gas was thought to emit 23% less global warming pollution than gasoline on a “well-to-tank” basis. The new data reduce CNG’s advantage to 14%.
Re-rating the 2011 models of the Honda Civic results in the Civic Hybrid now outscoring the Civic GX by 220 to 202 on the updated AutoEcoRating scale. Both are still a lot cleaner than the non-hybrid gasoline versions of the Civic (such as the LX and EX trims), which now score 137. Of course, the Honda Civic remains a leading green contender in its segment overall.
Model year 2012 versions of the standard gasoline and hybrid versions of the Honda Civic are now available, but final specs on the 2012 version of the CNG-fueled Civic GX were not released as of this writing. We’ll post a new update with ratings for the 2012 models (which all have higher fuel economy) once complete data are available, but we expect that the Civic Hybrid will remain tops as far as overall greenness is concerned.
And so the new part of the Civic lesson: automakers can build a very clean car — and the Honda Civic GX is as clean as it gets at the tailpipe, no doubt about that — but a vehicle’s overall environmental performance still suffers from the pollution involved in producing its fuel. Fossil gas is cleaner than fossil gasoline, but not by as much as everyone once thought.