Pros & Cons

This page is dedicated to the Pros and Cons of the Compressed Natural Gas Conversions for any and all vehicles.

Terms that will be frequently used:

CNG – Compressed Natural Gas

Bi Fuel -  A vehicle that can operate successfully on two separate forms of fuel. In our case CNG and gasoline.

GGE – Gasoline Gallon Equivalent. This is the unit that CNG tanks use to measure their fuel capacity.

Split fuel – A vehicle that operates on a combination of two fuels. In our case Diesel conversion kits mostly run on a combination of diesel and CNG. They are not solely reliable on CNG for fuel when they consume it. That is not to say that there are not diesels that have been converted to run on CNG completely, because it can be done and is done regularly but it is very expensive and I am not familiar with all that is done to the motor for it to be possible. So for our conversations when I am referring to diesel conversions I am talking about a split fuel conversion.

First of all we need to lay some boundries or assumptions in order to help you understand the benefits and drawbacks to a CNG conversion kits. We are going to base this discussion on a couple things;

  • In order for the conversion to make sense at all you need to have a local supplier of cng. This can be a public filling station or your own private filling station, or even access to a private filling station that you have permission to use. Without access to the compressed natural gas its not feasible to benefit from a CNG bi-fuel vehicle. 
  • Next we need to establish that these systems are SAFE. They CNG market has been around for a few years now and there are some things to avoid but in general they work and are even safer to operate than a regular fuel vehicle. 

On to the true subject material.


  1. Natural Gas is an abundant and renewable energy source.  The united states has so much gas in some areas we don’t know what to do with it. There is such an abundant supply across the US that many oil companies are burning off the natural gas from their wells so they can access the oil. Because the margins are so low it doesn’t provide enough of a benefit for them to capture and sell it so instead they waste it. Let me mention the fact that many countries already rely on natural gas for a secondary fuel supply to their vehicles. Many of the CNG kits come from the middle east, South America, and Europe. Some of these countries provide us with oil for our vehicles while they are burning natural gas in theirs because its so much cheaper to use.
  2. Natural Gas is cleaner burning than conventional oil. You can research the numbers and i’ve read that CNG is cleaner by up to 88% than conventional gasoline in regards to emmisions. The main byproduct of burning CNG is water and CO2. One of the only unclean byproducts of burning CNG is the Nitro oxides and they are so minimal its hard to get numbers and accurately count them to reference to gasoline burning motors. There is a debate on the fact that CNG produces more CO2 than gasoline and its worse on the environment according to some individuals.  However credit shouldn’t be given to this argument because it is so negligible compared to the huge reduction in real pollutants that aren’t emitted like the Hydro Carbon chains that can’t be absorbed into the environment and are the direct contributors to smog and pollution. When the second argument is recognized by the tree huggers then we can discuss the CO2.
  3. Natural Gas is generally significantly cheaper. Do a google search for Alternative fuel prices in your state and you should see that CNG is significantly less than regular gasoline or diesel.
  4. Because CNG burns so much cleaner there is less maintenance required on your motor. One of the main reasons you need to change your oil, apart from it breaking down over time, is that it becomes contaminated by the Hydro Carbon chains that speed up the decay of your oil. Because you aren’t producing these carbon chains your oil remains cleaner longer and your vehicle can go longer between oil changes. Normally it is recommended to change your oil 3ooo-4000 miles and some manufactures are now saying up to 70000 miles on your vehicle.  I personally don’t feel comfortable going 7K miles between oil changes without running a full synthetic but i do run 5000 miles on standard non synthetic oil and my oil is significantly cleaner than when it was  running on gasoline.
  5. Because most after market kits operate with the existing gasoline components you can run your CNG out then run on regular gasoline for an extended range above your normal gasoline range.


  1. Conversion Kits have an up front price tag to purchase and install. There isn’t a nice way to put it, it costs money to be cleaner and burn cheaper fuel. Funny how that sounds. Depending on how much you drive will depend on how quickly you can recapture the cost of the conversion and start saving money and the planet.
  2. Conversion kits can be relatively complex to install if you aren’t a mechanic or have the “know how” to work on vehicles. To the average person this can be a daunting task and if you aren’t someone who is familiar with mechanic work then I probably wouldn’t recommend doing it your self. There are more and more mechanics that are learning about the industry and becoming installers. If you need one go to and look under the cng mechanic forum. There is a list of mechanics in your state that can help and perform the conversion for you.
  3. You might live in an area that doesn’t have a CNG infrastructure available to take advantage of its benefits. Maybe you only have one filling station and its out of the way. It can be inconvenient to find a station to fill up that is close to home or work.
  4. You might not have the same capacity as regular gasoline.  What I mean is, because of the tank size and your vehicle you might only be able to fit a 5gge or 7 gge tank in your car so you might only get 100-150 miles out of a tank. This can be an inconvenience to people. I personally feel the cost savings is significant enough this point is negligible if you are using CNG.
  5. Available space might be an issue as well. To go along with number 4, the tanks are relatively large because of the materials that are used and the pressure they hold it takes up some space. If you are installing the system on a car you should count on loosing the majority of your trunk space unless you have something large like a crown victoria or something huge like that. Losing that trunk space is an inconvenience and can be a deal breaker for some people. If you are putting it on a truck you have more options,  in the bed just behind the cab or underneath the truck next to a frame rail if you are converting a larger truck like a 1/2-3/4 ton. Again you can be loosing bed space but is perfectly fine to set things on top of the tanks as long as it doesn’t risk damaging them or the valve.

So there you have what I think are the basic pros and cons of the compressed natural gas conversions. Let me know if you can think of anything else you would like me to add to the subject and I can review it and see if it is worthy of the conversation.