The Cleanest Cars on Earth?: Honda Civic GX and Other Natural Gas Vehicles (NGVs)

Honda Civic GX, NGV, Natural Gas Vehicle

Clean Burning Natural Gas Vehicles (NGVs) are hot commodities in some parts of the country, where fuel can sell for as low as $0.63 per gallon.

Unlike the world’s most fuel efficient car (VW’s 285 MPG bullet), the Honda Civic GX looks like a standard passenger vehicle. What makes it special is what you don’t see: tailpipe emissions that are often cleaner than ambient air.

The Civic GX is powered by compressed natural gas—methane—the simplest and cleanest-burning hydrocarbon available. With an economical 113-hp, 1.8-Liter engine, the EPA has called the Civic the “world’s cleanest internal-combustion vehicle” with 90% cleaner emissions than the average gasoline-powered car on the road in 2004.

And get this: in Utah, natural gas can be purchased for $0.63 per gallon.

At $24,590, buying a new Civic GX won’t exactly break your bank account, especially since up to $7,000 will come back to you in the form of state and federal tax credits. But don’t expect to find one easily. The car is only sold in two states, New York and California, and Honda can’t build them fast enough. One dealership said they have over 80 people waiting to buy.

It’s fairly obvious why densely populated states would be interested, especially since natural gas is a readily available source of heating fuel for many parts of the country. Most importantly, the Civic is the Eagle Scout of emissions certifications: it qualified for the California Air Resources Board’s Advanced Technology Partial Zero-Emission Vehicle (AT-PZEV) status, which means that it’s a Super-Ultra-Low-Emission Vehicle (SULEV) with zero-evaporative emissions. To qualify for AT-PZEV, the Civic must also carry a 15-year/150,000-mile warranty on emissions equipment. It also meets EPA’s strict Tier-2, Bin-2 and ILEV certification.

Despite getting the equivalent of a good but not quite amazing 36 MPG highway/24 MPG city, the American Council for an Energy-Efficient Economy (ACEEE) awarded the Civic the green ribbon as the greenest vehicle of 2008. That’s the fifth consecutive year it’s taken the top prize.

So what’s the downside?

Drawbacks to the Civic GX and other Compressed Natural Gas Vehicles

Earlier this week I was clued-in to the explosion in popularity of compressed natural gas (CNG) vehicles in Southern Utah, and their potential to overwhelm the 91 refueling stations already in place there.

That’s the biggest drawback to NGVs:

One way to get around this is to buy your own natural gas refueling station. Since a large number of us burn natural gas for heat, this doesn’t require much more than setting up a pump. The refueling kits, made by FuelMaker, will set you back about $3,500, but that can be offset by substantial tax credits.

  • Second drawback: since natural gas is a compressed fuel, the tank takes up some trunk space, and only holds the equivalent of 8 gallons of gasoline. Honda estimates the vehicle’s range to be 220 to 250 miles, although Consumer Reports claimed it was closer to 180 miles.

NGV enthusiasts are getting around range limitations (and vehicle scarcity) by converting their own vehicles to run on natural gas and adding spare tank capacity. Throwing extra tanks in the bed of a truck, for example, can boost driving range to around 600 miles. The best part about converting a vehicle (as opposed to the Civic GX) is that if you run out of CNG, the system automatically switches back to gasoline.

  • Third drawback: NGVs don’t provide that great of a reduction in greenhouse-gas (GHG) emissions when compared to their gasoline counterparts.

According to the industry group Natural Gas Vehicles for America (NGVA), the reduction is only 20%, which is about the same GHG reduction you get from corn-based ethanol. That doesn’t sound too impressive, but it’s still a reduction, and clean air could be worth it.

The big question mark is natural gas supply. If large amounts of biomethane can be produced from biomass (which is probably already done at your local landfill), the emissions reductions would be much greater.

But What About Natural Gas Supply?

Natural gas supplies 20% of all energy use in the US. According to NGVA: “Even if the number of NGVs were to increase 100-fold in the next ten years to 11,000,000 or roughly 5% of the entire vehicle market (a formidable goal), the impact on natural gas supplies and the natural gas delivery infrastructure would be small — equating to about 4 percent of total U.S. natural gas consumption.”

At first glance, that sounds pretty good, but any increase in natural gas usage means importing more fuel.

Taking a look at data from the Energy Information Administration, the US uses about 21.6 trillion cubic feet of natural gas per year, most of which is produced domestically (18.5 trillion cubic feet) with the difference being imported (4.2 trillion cubic feet). Proved natural gas reserves in the US amount to about 211 trillion cubic feet. If my math is correct, without taking into account any increase in demand, the US only has about 11.5 years of natural gas left. After that, we’re back to square one: importing oil from Russia, Qatar, Iran, and Saudi Arabia

Like petroleum, two-thirds of world natural gas supply exists in just a few countries. If we’re at all worried about having domestic (let alone renewable) energy sources, basing the future of US transportation on natural gas puts us right back in the same position we’re in now.

Also like petroleum, there is an “infinite supply” argument: “Don’t worry, we won’t run out… promise.” NGVA says that if we can tap into methane hydrate ice formations that exist under 1000 feet of water at the bottom of the arctic oceans, we’ll be just fine. Right now, this is about as plausible as time travel, and methane hydrates serve a very important function—they’re a crucial sink for carbon dioxide in the global carbon cycle.


Whether or not we’ve learned our lesson about importing foreign energy, natural gas could still provide a functional infrastructure and technology for transition to hydrogen fuel cells. Natural gas is currently the number one feedstock for producing hydrogen, and refueling stations along California’s hydrogen highway may produce the fuel by reforming natural gas on-site. Basically, this gives us a transition fuel until we figure out how to make hydrogen sustainably.

As for the Honda Civic GX, it may be the cleanest-burning vehicle on the market, but the drawbacks listed above are likely to keep NGVs out of mainstream production for the forseeable future. It seems unlikely that natural gas will stay as cheap as it currently is in Utah, but relatively low pricing could keep the car’s popularity high in some areas. It will be interesting to see how things resolve there.

For more on the Honda Civic GX, see Honda’s Website and Consumer Reports. See more pictures below.

For more on Natural Gas, see Natural Gas Cars: CNG Fuel Almost Free in Some Parts of the Country.

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Honda Civic GX, NGV, natural gas vehicle

Honda Civic GX, NGV, natural gas vehicle
Photo Credit: Honda

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Add a comment or question


  1. Rubbish. Hydrogen is far cleaner because it has *zero* harmful emissions, only water vapor.

  2. What about the danger of natural gas? Isn’t it extremely explosive? How does that work out?


    Estimates of Available Natural Gas supplies in the United States range from 1,127 - 1,451 Trillion Cubic Feet of Natural Gas.

  4. Just like any problem we need to attack fuel usage from many angles. The government should throw down the hammer and make tighter restrictions on the type of cars you are allowed to drive. You can still buy any car you want but you will just have to pay extra tax to buy a large car when you don’t need to be driving one. All of these 20mpg cars are just a total waste. We could reduce usage by 50% right off the bat by selling cars that get 40mpg.

  5. The use of the term “explosion” seems to be a poor choice here:

    “Drawbacks to the Civic GX and other Compressed Natural Gas Vehicles

    Earlier this week I was clued-in to the explosion of compressed natural gas (CNG) vehicles in Southern Utah…”

    I thought they were literally exploding until I clicked the link.

  6. Know the difference between ‘proven reserves’ and ‘proved reserves’. Proved reserves have increased yearly within the US. As stated by Strawgate, ‘Estimates of Available Natural Gas supplies in the United States range from 1,127 - 1,451 Trillion Cubic Feet of Natural Gas.’

  7. Natural gas will come a time it will be expensive and the criss will be the same as oil now. Both hydrogen and methane are highly explosive. Hydrogen is more environmental friendly though is explosive but we need that explosive part of it to make our car run. On my guess compress air, water and electricity can work the magic for our transport.

  8. All car companies seem to be looking for a single option replacement to the long running fossil fuels vehicles we are all used to. With the available technologies many seem like good solutions for specific niches. As for the natural gas car why are they not looking at extending the functionality by making a natural gas hybrid. If the natural gas engine were used as the charging center for the electric vehicle its lower horsepower output would not be as much of an issue. Added driving range or smaller fuel storage tanks should also be a side result. Who is doing this type of vehicle?

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