CNG: compressed natural gas as a vehicle fuel
CNG is compressed natural gas, mostly methane, sold by weight rather than by volume. It powers dedicated, bi-fuel or converted vehicles and is common only in a handful of countries with well-established infrastructure.
In this entry
What CNG is — definition, full form, and meaning
CNG stands for Compressed Natural Gas — the CNG full form tells you exactly what it is: natural gas compressed to around 200–250 bar so a useful amount fits in a vehicle tank. The CNG meaning in a fuel context is simply this: the same methane piped into homes for heating and cooking, stored at very high pressure rather than at pipeline pressure. The CNG definition is consistent worldwide — it is always compressed methane, always sold by weight (kg) rather than by volume, and always requires dedicated high-pressure vehicle systems.
Is CNG a natural gas? Yes — CNG is natural gas in compressed form. It is not a petroleum product in the conventional sense: methane occurs alongside crude oil in underground reservoirs, but it is a chemically distinct compound. Which gas is CNG? It is primarily methane (CH₄), typically 85–95% by volume, making up the bulk of the CNG gas mixture. Is CNG a liquid? No — unlike LPG, which liquefies under moderate pressure, methane remains a gas at vehicle storage conditions (200–250 bar). CNG pressure in vehicle tanks is 200–250 bar (≈ 3,000–3,600 psi) — far higher than LPG's ≈ 8 bar — which is why CNG tanks are heavy and purpose-built.
What is CNG made from? CNG is made from natural gas — extracted from underground wells, processed to remove water and impurities, then compressed at a filling station or industrial compressor. Where do we use CNG? As a vehicle fuel for cars, buses, taxis, and trucks; as a fuel for forklift trucks and port equipment; and in some markets as a household energy source. It is a different fuel family from petrol, diesel, and LPG — it needs its own storage tanks and refuelling equipment.
How CNG is measured and sold
Petrol and diesel are sold by the litre or gallon because they're liquids with a fixed volume at normal pressure. CNG is a compressed gas, so it's usually priced by weight instead.
Because CNG is priced by weight in most markets, a price shown "per litre" for CNG isn't meaningful on its own. Always check the unit before comparing it with a liquid fuel's price per litre.
Which vehicles can use it
Not every vehicle can use CNG. It needs a pressurised tank and fuel system built or fitted for the purpose.
Is it cheaper to run?
CNG is usually cheaper per unit of energy than petrol, partly because in many markets it is taxed more lightly. As with E85, the fair comparison is cost per distance rather than price per unit, since a CNG vehicle's range per tank and per kilogram differs from a petrol vehicle's range per litre.
See E85 for the same cost-per-distance ideaWhere CNG is common
CNG use is concentrated in a handful of markets that built out the infrastructure and vehicle fleet over many years, rather than being spread evenly worldwide.
How this shows up on FuelTheGuide
We show CNG as its own grade, priced per kilogram where a country publishes it, separate from petrol, diesel and LPG. Most countries have no CNG data at all, and we show that as a dash, never as a zero.
CNG appears as its own grade, separate from petrol, diesel and LPG, only for the countries that publish it.
Questions and answers
Is CNG the same as LPG?
No. CNG is mostly methane, kept as a gas under high pressure, while LPG is propane and butane, kept as a liquid under much lower pressure. They use different tanks and different refuelling equipment. The US Department of Energy's Alternative Fuels Data Center explains the differences in detail.
Why is CNG usually cheaper than petrol?
Because CNG is taxed more lightly than petrol in many markets. The underlying natural gas commodity is often cheaper than crude-derived fuels, and in many countries the excise duty on CNG is lower, sometimes as an incentive to shift towards lower-emission fuels.
Do CNG vehicles have a shorter range than petrol ones?
Usually, yes. CNG tanks hold less energy than a petrol tank of similar size, partly because of the weight and volume needed to store it safely under pressure. Bi-fuel vehicles carry a petrol tank as backup, which extends effective range.
Is CNG safe?
CNG vehicles have a strong safety record. The tanks are built to withstand significant impact without rupture, and because methane is lighter than air it disperses quickly if there is a leak, rather than pooling on the ground like petrol vapour or LPG. The US DOE Alternative Fuels Data Center covers CNG vehicle safety in more detail.
What does CNG stand for?
CNG stands for Compressed Natural Gas — the full form of CNG is a descriptor of how the fuel is stored. CNG meaning in a vehicle context is natural gas (mostly methane) compressed to around 200–250 bar and dispensed by weight (kg) rather than by volume. The cng definition is consistent globally: it is the same gas used for home heating and cooking, just compressed into a high-pressure vehicle tank. CNG fuel type is categorised separately from petrol, diesel, and LPG because it requires different vehicle systems and infrastructure.
Is CNG a natural gas?
Yes — CNG is natural gas in compressed form. The gas used in CNG is primarily methane, the same hydrocarbon piped into homes. It is not a petroleum product in the conventional sense, even though it often co-occurs with crude oil deposits. CNG is made from natural gas extracted underground, processed to remove impurities, then compressed at a dispensing station. Which gas is CNG? It is mostly methane (CH₄), typically 85–95% by volume.
What pressure is CNG stored at?
CNG pressure in vehicle tanks is typically 200–250 bar (roughly 3,000–3,600 psi). This is much higher than LPG (≈ 8 bar) and is the reason CNG is a compressed gas rather than a liquid. The high pressure also explains why CNG is not a liquid — it remains in its gas phase even at these pressures, unlike propane or butane which liquefy at low pressure. The heavy high-pressure tanks required are a key trade-off compared to petrol or LPG systems. See ISO 15500 for CNG vehicle system standards.
CNG meaning and the role of compressed natural gas in transport
What is CNG? In the broadest sense, CNG meaning is simply compressed natural gas — methane extracted from underground reservoirs, processed to remove impurities, then compressed to 200-250 bar for dispensing into vehicle tanks. The term "compressed natural gas" distinguishes it from LNG (liquefied natural gas), which is cooled to -162 degrees C for bulk marine transport, and from pipeline natural gas, which flows at much lower pressures. The U.S. EIA natural gas explainer provides comprehensive data on how natural gas is used across sectors, including as a vehicle fuel.
CNG adoption is growing in markets where domestic natural gas production keeps feedstock costs low — notably Pakistan, Iran, Argentina and Italy. The IEA's gas technology pages track how natural gas vehicles fit into the global energy transition. For fleet operators considering a switch, the key trade-off is lower fuel cost per kilometre versus the higher upfront cost of CNG tanks and the more limited refuelling infrastructure compared with petrol or diesel. The European Commission's alternative fuels strategy outlines the EU's approach to expanding CNG and other alternative fuel infrastructure.
More questions
What is the full meaning of CNG in the fuel context?
CNG stands for compressed natural gas. The CNG meaning in a vehicle context is natural gas (mostly methane, CH4) compressed to around 200-250 bar and dispensed by weight (per kilogram) rather than by volume. It is the same gas used for home heating and cooking, just stored in a high-pressure vehicle tank. CNG is categorised as a separate fuel type from petrol, diesel and LPG because it requires different vehicle systems and dedicated refuelling infrastructure.
Sources and further reading
- Natural gas as a vehicle fuel US Department of Energy, Alternative Fuels Data Center, afdc.energy.gov
- CNG vehicle statistics by country International Association for Natural Gas Vehicles, ngvglobal.org
- Fuel prices tool and grade lists OpenVan.camp, openvan.camp/compare/fuels/fuel-prices