What is CNG

CNG refueling

A short time ago the vast majority of cars were diesel or gasoline. There were practically no other options. However, in the last five years everything has changed a lot. Conventional hybrid vehicles have notably increased their sales, plug-in hybrids have been correctly positioned as another alternative, the development of electric vehicles is advancing by leaps and bounds and, in addition, other Two fuels have become very important: CNG and LPG.

In this article we will explain everything about CNG in a simple way. We are going to answer basic questions such as what is CNG, where do you get this fuel, what is fifth generation CNG, how to find gas stations that supply this fuel, what cars use CNG, what is the difference in price compared to a normal car and how a car is converted to natural gas (and the price of the conversion).

The first thing to note is that CNG stands for Compressed Natural Gas.. We should not confuse it with LPG, which is Liquefied Petroleum Gas. Both are fuels and are used in vehicles, but they are different and one does not work for the other. The adaptation of the engines is also different.

What is LPG
Related article:
What is LPG? Possible car problems and their solutions

Before getting into the thick of this article, I wanted to mention that the use of CNG in vehicles is not something of recent times. Many Bus fleets, especially urban ones, have been using Compressed Natural Gas for years to power their thrusters. In this way, in addition to reducing pollution in cities, companies also reduce their expenses.

Where do you get CNG from?

Like crude oil, CNG is extracted from bags on the ground, but natural gas does not come out of the same bags as oil. Compressed Natural Gas is basically made up of methane (almost 90%). Some other compounds are nitrogen and hydrocarbons, but in negligible proportions. Therefore, it is much less polluting than gasoline or diesel.

It is a natural organic resource.

A positive aspect is that does not need a long treatise on refinementsuch as gasoline or diesel. This is one of the reasons why the cost is much lower. In any case, a series of processes must be carried out to purify it and thus be able to use it as fuel in our engines.

CNG fuel level indicator

The natural gas used in cars is the same as the one we have in our homes, but for its operation it must be subjected to high pressure.

Advantages of CNG

One of the main advantages is that CNG is a noticeably cleaner fuel than gasoline or diesel. At the time of combustion in the cylinders, the result of the explosions is practically CO2 (carbon dioxide) and H2O (water). The amount of nitrogen oxides and soot particles is practically nil.

That is why they are so clean. In fact, the combustion of CNG is less polluting than that of LPG itself, which is why they are so highly regarded by the European Union.

Due to its low pollution and the large reserves of natural gas (although they are finite), this fuel is subsidized by the EU. Although it depends on many factors and is variable for each supplier, the price of CNG at the beginning of 2020 was between 0,8 and 0,95 euros per kilo. About 40% cheaper than gasoline.

Therefore, it is not difficult to make the extra initial outlay profitable in a short time. Of course, it will depend on the number of annual kilometers traveled and the difference in price with gasoline.

We must not forget that all modern passenger cars that use CNG as fuel, regardless of their displacement or power, benefit from the Eco label of the DGT. If our car left the factory with a traditional system and was later adapted to natural gas, it is entitled to the Eco environmental label.

Logically, being a vehicle that pollutes little with the environment, in Spain it has certain tax advantages. For example, the registration tax is eliminated and the annual circulation tax (the little number we pay every year) is considerably reduced. We must not forget that, by having the Eco label, we can access the center of large cities in episodes of high pollution and that we have great advantages when parking in a regulated parking area.

Disadvantages of CNG

Seat Ibiza TGI CNG

But not everything are advantages. There are also some cons to these CNG vehicles. The main disadvantage is that, at the moment, there are not many gas stations that have Compressed Natural Gas dispensers. It is something that must be taken into account when evaluating whether to acquire a CNG car. When making a long trip, it is necessary to plan the route well and, for routine journeys, it will be better to have a station that has this fuel close to home.

CNG cars also have a fuel tank and can run perfectly on either of these two fuels. However, to make room for the natural gas tank, brands considerably reduce the capacity of the gasoline tanks, so their autonomy with this fuel is limited, and they also tend to lose cargo space.

Continuing with the inconveniences, when buying the car (already prepared from the factory), its price is usually higher than an equivalent gasoline car. However, due to the low cost of this fuel and its efficiency, it will not take long to cover this amortization. Of course, it must be taken into account that prices can change, and CNG is more advantageous the greater the price difference between gasoline and diesel.

Currently the price difference between a gasoline car and a CNG car is usually around 2.000 euros, with similar benefits.

Experts in transformations and the manufacturers themselves say that maintenance should be more strictly. It is true that a well-maintained engine should last as long as a similar gasoline engine. However, it is necessary to be more aware of the revisions despite the fact that the combustions are cleaner. The reason is that CNG is somewhat more corrosive and the entire CNG system must be checked every "x" years, when the manufacturer recommends it.

Differences between LPG and CNG
Related article:
Cars with LPG and CNG in 2022: differences and prices

Finally, with the same mechanics and driving, a car needs to spend a little more CNG than gasoline to cover the same distance; around 5%. It is also true that performance (power and torque) is reduced by about 10%, although in normal driving situations it is difficult to perceive this. In summary, it yields very little less and spends very little more; or what is the same, the difference is almost imperceptible.

Gas stations with CNG

As we mentioned in the disadvantages section, there are currently not many service stations that have compressed natural gas pumps for cars. Of course, it is true that they are becoming more and more and there are programs to expand them.

According to GASNAM (Iberian Association that promotes the use of Natural Gas and Renewable Gas in land and sea mobility), there are currently 81 active CNG gas stations on the peninsula. In the same way, they communicate that there are another 32 in project or in works that will be opened soon. Catalonia (19), Community of Madrid (19), Castilla La Mancha (9), Valencian Community (9) and Andalusia (8) are the autonomous communities with the most CNG refueling points.

CNG cars

Regarding the car manufacturers that offer their “home” products with Compressed Natural Gas, they are not all, but it is true that more and more are investigating and trying to put products with this fuel on the market. Currently, the manufacturer with the most CNG models is the Volkswagen Group. In fact, the Spanish brand Seat is the one that has been in charge of the study and development of these systems for the entire group.

The most commercialized are the Seat Ibiza, Seat León, Seat Arona, Skoda Octavia and Fiat Panda. There are also models from Audi, such as the A3 or A4, and from Volkswagen, such as the Golf or Polo. As we said, Seat seems to be the one who has taken the CNG flag in Europe.

Price of models with CNG (how much more expensive Vs gasoline model)

As we mentioned before, it has always been said that there is a notable price difference when buying a gasoline car and another identical model with similar benefits with CNG; around 2.000 euros. The best way to compare it is by taking a look at the brand's configurators. We have opted for one of the most demanded cars in our country, the Seat Ibiza.

According to the configurator of the Spanish brand, a Seat Ibiza 1.0 TGI 90 CV (CNG) in Style Plus finish and without adding extras, has an official price of 17.290 euros. On the contrary, in an Ibiza 1.0 TSI 95 CV (petrol) in the same finish and without extras we see a price of 15.580 euros. The difference according to the configurator is 1.710 euros. For that matter, the same car with a 95 hp TDI (diesel) engine costs 17.750 euros, 460 euros more expensive than the CNG and 2.170 euros more than the gasoline one.

Convert car to CNG

If we have a gasoline car and we want to convert it to CNG, there are not too many problems. The only thing we must take into account is that it must be at least Euro3, that is, the cars that currently have the DGT sticker B (yellow); from there on.

DGT emission labels
Related article:
The DGT classifies cars based on pollution with colored labels

Bluemotion TGI Volkswagen CNG

Depending on whether they use mechanics with indirect or direct injection, the price will be higher or lower. The indirect injection (which as a general rule tend to be somewhat older) are somewhat cheaper. The higher the number of cylinders, the price also rises. As a general rule, the transformation costs between 2.000 and 3.000 eurosalthough it depends on several factors. Among other things, because there are cars in which it is easier than others (more or less labor time and more or less modifications to the vehicle).

Logically, this transformation to CNG must be carried out in an approved center. Once our car has already been modified, the first thing we must do is pass the ITV with all the pertinent documentation of the vehicle and the one that they have given us in the workshop about the modification. If everything goes according to plan and there are no incidents on the ITV, the next step is go to a Traffic Headquarters so that the record of our vehicle is modified and, consequently, they give us the Eco label of the DGT.

Can a diesel vehicle be converted to CNG?

The answer is yes, you can convert a diesel vehicle to CNG. However, due to the diesel duty cycle (which is different from gasoline) and the properties of natural gas, it is more complicated and much more expensive than in a gasoline engine. It costs much more to return on investment. Therefore, we do not see diesel CNG cars. However, some industrial vehicles, trucks or buses have carried out these adaptations. The reason is that, since these vehicles spend so much fuel, it is more feasible to be able to recover the investment over time and kilometers.


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