CNG vs LPG: Fuel Efficiency, Cost & Emissions Compared
CNG (Compressed Natural Gas) is methane stored at high pressure; LPG (Liquefied Petroleum Gas) is propane & butane liquefied under moderate pressure. Both burn cleaner than petrol, but they’re chemically and physically different fuels.
At the pump they look similar—nozzle, hose, click—so drivers assume they’re interchangeable. Fleet managers swap one for the other chasing lower prices, then wonder why range or pickup changes. Same city, same tank, totally different energy stories.
Key Differences
CNG packs 9 MJ/L and needs 200-bar tanks; LPG carries 25 MJ/L in lighter 10-bar cylinders. CNG cars cost ₹60k more upfront yet run ₹2.5/km cheaper on fuel; LPG conversions are cheaper but fuel price swings harder. CNG emits 23% less CO₂ and near-zero PM; LPG cuts CO₂ by 11% but adds slightly more NOx.
Which One Should You Choose?
City commuter? CNG wins on daily rupees and clean-air zones. Highway hauler or rural rider? LPG’s higher energy density keeps your pickup light and range anxiety low. Check local pump density and conversion incentives before you commit.
Can I switch my petrol car to CNG or LPG?
Yes, certified retrofit kits exist; CNG needs stronger tanks and a new ECU map, LPG uses simpler vapor or liquid injection systems.
Do both fuels work in cold winters?
CNG flow drops slightly below 5 °C but stays usable; LPG vaporizes easily down to –40 °C, making it more cold-proof.
Which is safer in a crash?
CNG tanks are thicker and leak upward, dispersing quickly; LPG is heavier and can pool, but both have automatic shut-off valves and meet strict safety norms.