With petrol crossing ₹100 per litre in most Indian metros and CNG available at ₹75–95/kg, factory-fitted CNG cars now deliver running costs of ₹2.50–3.50 per km — roughly half the cost of equivalent petrol vehicles. 41 CNG car models are available in India in 2026, from the ₹3.50L Maruti S-Presso CNG to the ₹19.72L Maruti Grand Vitara CNG. This guide covers the 10 best CNG cars in India by mileage, price, and features — with honest assessments of which buyer profile each car is actually best for.
Rising fuel prices have made CNG cars one of the most practical choices for Indian buyers in 2026. With petrol crossing ₹100 per litre in most metros and CNG offering 30 to 40 per cent lower running costs, more families are switching to factory-fitted CNG models from Maruti Suzuki, Tata, Hyundai, Toyota and others. There are 41 CNG cars currently available for sale in India at starting prices from ₹4.62 lakh. The most popular CNG cars are Maruti Suzuki Brezza, Tata Punch, Maruti Suzuki Fronx, and Maruti Suzuki Swift. Tata Punch CNG delivers an ARAI-certified mileage of 26.99 km/kg with twin-cylinder iCNG technology. Factory-fitted CNG is strongly preferred over aftermarket kits — manufacturer systems ensure proper engine tuning, warranty coverage, and safer storage. Factory-fitted CNG matters for three reasons: engine ECU calibration for CNG fuel characteristics (aftermarket kits run on original petrol ECU, causing inefficiency), warranty coverage (aftermarket CNG voids manufacturer warranty on engine components), and boot-integrated cylinder design (less boot space loss vs aftermarket cylinder fitting). This guide covers only factory-fitted CNG options.
Best CNG cars India 2026: Highest mileage: Maruti Suzuki Celerio CNG (35.6 km/kg), Maruti WagonR CNG (34.05 km/kg), Maruti Dzire CNG (33.73 km/kg). Best value under ₹10L: Tata Punch CNG (₹5.70L, 26.99 km/kg, 5-star GNCAP), Maruti Swift CNG (₹5.79L), Maruti Fronx CNG (₹6.85L). Only premium SUV CNG: Tata Nexon CNG (17.44 km/kg) and Tata Altroz iCNG (27.8 km/kg, only factory-CNG hatchback). 7-seater CNG: Maruti Ertiga CNG and Toyota Rumion CNG (26.11 km/kg). Running cost: approximately ₹2.50–3.50/km vs petrol's ₹6.50–7.50/km in city.
Why Buy a Factory-Fitted CNG Car — vs Aftermarket CNG Kit
| Factor | Factory-Fitted CNG | Aftermarket CNG Kit |
|---|---|---|
| Engine ECU tuning | Manufacturer-calibrated for CNG fuel — optimal air-fuel ratio, ignition timing | Runs on petrol ECU — CNG combustion characteristics not matched, lower efficiency |
| Warranty | Full manufacturer warranty maintained | Voids manufacturer engine warranty — significant financial risk |
| Safety | Cylinder tested, positioned, and mounted by manufacturer. Burst disc safety valve included | Installation quality variable — cylinder positioning and mounting varies by installer |
| Boot space | Cylinder integrated under boot floor in most models (minimal boot loss) | Large cylinder in boot — significant boot space reduction |
| Resale value | Specific CNG variant resale — factory CNG commands premium in used car market | Lower resale — aftermarket CNG viewed skeptically by used car buyers |
| Mileage | Higher — factory calibration optimises CNG fuel efficiency | Lower than factory equivalent — ECU mismatch reduces efficiency by 10–15% |
CNG cars offer several advantages over petrol vehicles — lower fuel expenses, fewer emissions, and with factory-fitted systems, full warranty coverage. However, CNG cars may have limited availability of fuelling stations and slightly lower power output compared to petrol vehicles. CNG infrastructure is strong in Delhi, Mumbai, Ahmedabad, Surat, Pune, and Bengaluru — moderate in Hyderabad, Chennai, Kolkata. Before buying any CNG car, verify CNG station density on your specific daily commute route. In smaller cities and rural areas, CNG availability may make refuelling inconvenient.
Top 10 Best CNG Cars in India 2026
Maruti Suzuki Celerio CNG achieves 35.6 km/kg ARAI mileage — the highest of any CNG car in India in 2026, starting at approximately ₹4.70 lakh ex-showroom. The Celerio's 1.0L K10C engine is the smallest displacement CNG engine in Maruti's lineup — the combination of light body weight and small engine achieves exceptional CNG efficiency. Running cost at ₹90/kg CNG and real-world ~22 km/kg city: approximately ₹4.10/km — the lowest absolute running cost of any car in India except pure EVs. The Celerio's practical limitations: small cabin (tight rear for adults), limited features, but the lowest running cost makes it the correct choice for daily urban commuters doing 1,500+ km monthly who need pure economy. Also available as Celerio VXi CNG with automatic (AGS) in select markets.
Maruti Suzuki WagonR CNG delivers 34.05 km/kg ARAI mileage, starting at approximately ₹5.47 lakh ex-showroom — India's most popular CNG hatchback by sales volume. The WagonR's tall-boy body design provides more headroom and shoulder room than the Celerio — rear passengers sit upright rather than reclined, making it more practical for 4-person family use. The CNG boot cylinder fits under the false floor in most variants, preserving useful boot space. Available in 1.0L and 1.2L variants — the 1.0L CNG is the economy pick, the 1.2L provides more power on highways. WagonR CNG's case: high mileage, tall comfortable cabin, lowest Maruti running cost in a practical family size, excellent Maruti service network across all of India. The AGS automatic is available in CNG in select markets — useful for city stop-go.
Maruti Suzuki Dzire CNG is rated as the best CNG car by user reviews — known for mileage and value for money. Dzire has a 5-star safety rating. The Dzire CNG brings sedan practicality — separate boot (CNG cylinder in boot reduces usable space vs petrol, but 378L → ~280L usable remains adequate for most needs), more premium interior vs WagonR, and 5-star BNCAP safety. At ~33.73 km/kg ARAI and real-world 20–22 km/kg, the Dzire CNG's running cost at ₹90/kg is approximately ₹4.09–4.50/km city — comparable to WagonR but in a more premium sedan format. The Dzire CNG is the best CNG car for: cab and taxi operators (high daily mileage, sedan preference for passenger comfort), families who want sedan styling with CNG economy, and buyers where boot space reduction is acceptable for the fuel saving. See our Maruti Dzire price guide for the complete variant lineup.
Tata Punch CNG delivers an ARAI-certified mileage of 26.99 km/kg with twin-cylinder iCNG technology — available under ₹10 lakh ex-showroom with a 5-star Global NCAP safety rating. The Punch CNG's twin-cylinder system is its key technical differentiator — two smaller cylinders distributed under the boot floor rather than one large cylinder, providing better boot space retention and weight distribution vs single-cylinder CNG systems. The 5-star Global NCAP rating is the strongest safety certification in this price band for any CNG car — no other CNG car under ₹8L has a 5-star Global NCAP. The Tata Punch became India's best-selling car in June 2026, climbing from fourth to first position in the sales charts. For families who want safety + CNG economy in a compact SUV body: the Punch CNG is uniquely positioned. Not available with automatic — MT only in CNG.
Tata Altroz CNG starts at approximately ₹7.30 lakh ex-showroom. The Altroz iCNG occupies a unique position — it is the only premium hatchback (competing with i20, Baleno) to offer factory-fitted CNG. The i20 and Baleno do not have factory CNG. At 27.8 km/kg ARAI and real-world 19.80 km/kg city (CarWale tested), the Altroz iCNG delivers the lowest running cost in the premium hatchback segment. The CNG AMT launched in May 2026 (₹8.70L ex) adds automatic transmission to CNG — a genuinely unique combination in Indian hatchbacks. 5-star Global NCAP safety standard across all Altroz variants. For premium hatchback buyers who want CNG economy without compromising on cabin quality or safety: Altroz iCNG is the only option. See our Tata Altroz price guide for the complete CNG variant lineup.
Maruti Suzuki Fronx CNG starts at ₹6.85 lakh ex-showroom — one of the most popular CNG compact crossovers in India. The Fronx CNG at 28.51 km/kg ARAI delivers the best mileage among compact crossover-style CNG cars — better than the Brezza CNG (25.51 km/kg) and significantly better than the Nexon CNG (17.44 km/kg). The Fronx is based on Baleno's platform with a crossover body — it brings sunroof (from Sigma+ variant), wireless CarPlay, and connected car features in a compact SUV silhouette. For buyers who want the crossover styling of a small SUV with hatchback-like CNG mileage, the Fronx CNG is the correct pick. See our Maruti Fronx price guide for variant-wise details.
Maruti Suzuki Brezza CNG is priced from ₹9.30 lakh on road, making it one of the most feature-rich CNG compact SUVs in India. Maruti Suzuki Brezza starts at ₹7.40 lakh ex-showroom. The 2026 Brezza facelift brings new styling, updated features, and a new 1.0L turbo petrol engine option alongside the standard 1.5L. The CNG variant uses the 1.5L K15C naturally aspirated engine. 25.51 km/kg ARAI. The Brezza CNG's advantage over Fronx CNG: larger SUV body with more ground clearance, more established compact SUV reputation, wider Maruti service network. For buyers wanting a proper compact SUV (not a crossover) with factory CNG: Brezza is the established choice. See our Maruti Brezza price guide.
Maruti Suzuki Ertiga CNG and Toyota Rumion CNG are the two factory-fitted 7-seater MPVs with CNG in 2026. Both share the 1.5L K15C engine and 26.11 km/kg ARAI mileage. The Ertiga CNG is India's best-selling 7-seater CNG MPV — 3-row seating, comfortable for 6 adults, sliding rear doors on the XL6 variant, and the 26.11 km/kg ARAI CNG mileage that makes large-family transport economical. Running cost at ₹90/kg CNG and 18 km/kg real-world (7 adults, AC, city): approximately ₹5/km — split across 7 passengers = ₹0.71/person/km. No other 7-seater vehicle format delivers this per-person running cost. Toyota Rumion CNG is the identical product with Toyota badging — choose based on dealership access. Both offer 6-year/1,50,000 km warranty for the engine.
Maruti Suzuki Swift CNG starts at ₹5.79 lakh ex-showroom — one of the most popular CNG hatchbacks alongside WagonR and Fronx. The 2024-generation Swift brought the new 1.2L Z-Series engine (more refined, Euro-6 equivalent) replacing the old K-series. Swift CNG uses this new engine — more refined idle, better NVH vs the old Swift CNG. The Swift's premium over WagonR CNG (₹5.47L): approximately ₹32,000 for a sportier exterior design, slightly more premium cabin, and the Swift badge. Running cost and mileage are comparable to WagonR CNG at similar real-world conditions. For buyers who want hatchback style (Swift is the sportier-looking option) vs tall-boy practicality (WagonR): the ₹32,000 decision is essentially about design preference. Swift CNG is not available with AMT automatic — MT only.
Tata Nexon CNG offers 17.44 km/kg ARAI mileage — positioned as a premium SUV CNG option, best suited for buyers prioritising space and safety over absolute fuel economy. The Nexon CNG's mileage is the lowest on this list (17.44 km/kg ARAI vs Celerio's 35.6 km/kg) — but it is a proper mid-size compact SUV, not a hatchback. The comparison should be: Nexon CNG at 17.44 km/kg vs Nexon petrol at ~17 kmpl ARAI — marginal mileage improvement on paper, but CNG's lower per-kg cost still delivers approximately 35% running cost saving vs equivalent petrol. The Nexon CNG is for buyers who specifically want: a larger SUV body, 5-star GNCAP safety, Tata's proven SUV platform, and factory CNG — not maximum mileage. See our Tata Nexon price guide.
CNG Car Comparison Table — All Top 10 (July 2026)
| Car | Price (ex) | CNG Mileage | Body | Safety | Best For |
|---|---|---|---|---|---|
| Maruti Celerio CNG | ~₹4.70L | 35.6 km/kg | Hatchback | 2-star GNCAP | Maximum economy |
| Maruti WagonR CNG | ~₹5.47L | 34.05 km/kg | Tall hatchback | — | Family hatchback economy |
| Maruti Dzire CNG | ~₹6.79L | 33.73 km/kg | Sedan | 5-star BNCAP | Sedan CNG, cab use |
| Tata Punch CNG | ₹5.70L | 26.99 km/kg | Micro-SUV | 5-star GNCAP | Safe budget CNG SUV |
| Tata Altroz iCNG | ~₹7.31L | 27.8 km/kg | Premium hatchback | 5-star GNCAP | Premium hatchback CNG |
| Maruti Fronx CNG | ₹6.85L | 28.51 km/kg | Compact crossover | — | Crossover CNG + features |
| Maruti Brezza CNG | ₹7.40L | 25.51 km/kg | Compact SUV | 5-star BNCAP | Compact SUV CNG |
| Maruti Ertiga CNG | ~₹8.35L | 26.11 km/kg | 7-seat MPV | — | 7-seater family CNG |
| Maruti Swift CNG | ₹5.79L | ~28–30 km/kg | Hatchback | 5-star BNCAP | Style + economy |
| Tata Nexon CNG | ~₹8.35L | 17.44 km/kg | Compact SUV | 5-star GNCAP | SUV + 5-star safety CNG |
CNG Car Running Cost Comparison (2026)
| Fuel Type | Price | Real-World Mileage | Cost per km | Monthly cost (1,500 km) |
|---|---|---|---|---|
| CNG (Celerio best case) | ₹90/kg | 22 km/kg city | ~₹4.09/km | ~₹6,136 |
| CNG (WagonR/Dzire avg) | ₹90/kg | 20 km/kg city | ~₹4.50/km | ~₹6,750 |
| CNG (Altroz/Fronx avg) | ₹90/kg | 18 km/kg city | ~₹5.00/km | ~₹7,500 |
| Petrol (hatchback avg) | ₹100/L | 14 kmpl city | ~₹7.14/km | ~₹10,714 |
| Diesel (compact SUV avg) | ₹90/L | 18 kmpl city | ~₹5.00/km | ~₹7,500 |
CNG payback period over equivalent petrol: at ₹3,000–4,000/month saving (CNG vs petrol), and CNG premium of ₹70,000–1,00,000 over equivalent petrol variant: payback in 18–33 months. After payback: pure savings. At 2,000 km/month: payback in 12–18 months. At 1,000 km/month: payback in 30–50 months — CNG may not be economically justified for low-usage buyers. CNG is recommended for: 1,500+ km monthly city driving, commuters with CNG station on daily route, cab and commercial use, families with 2+ daily drivers sharing one car.
CNG Car Buying Tips — India 2026
- Check CNG station density on your specific route before buying: CNG infrastructure in India is excellent in Delhi-NCR (450+ stations), Mumbai (250+ stations), Ahmedabad, Surat, and Pune. In Bengaluru, Chennai, and Hyderabad: growing but thinner. Before buying any CNG car, search "CNG station near [your area]" on Google Maps and count stations within 5 km of your home and office. If there are fewer than 3 stations on your daily route: CNG may cause inconvenience. One under-discussed issue: CNG station queues can be 15–30 minutes at peak times (7–9 AM, 6–8 PM) in high-density areas — factor this time cost into your decision
- Factory-fitted only — never aftermarket: Factory-fitted CNG is strongly preferred over aftermarket kits — manufacturer systems ensure proper engine tuning, warranty coverage, and safer storage. The upfront premium of factory CNG over equivalent petrol (₹70,000–1,00,000) is significantly less than the risk and efficiency loss of aftermarket systems. If a dealer offers to "convert" your new petrol car to CNG post-purchase: decline. Buy the factory CNG variant directly
- Boot space check — twin-cylinder is better: Tata's iCNG twin-cylinder system (Punch, Altroz, Nexon, Tiago) places two smaller cylinders below the boot floor — minimal boot space reduction. Maruti's single-cylinder system places one larger cylinder — more boot space loss. Compare: Tata Punch CNG boot space loss is less than Maruti WagonR CNG. If boot space matters: choose Tata twin-cylinder iCNG over Maruti single-cylinder equivalents
- CNG automatic cars are rare but available: Direct factory-fitted automatic CNG cars are limited. The Maruti Suzuki Celerio AMT and WagonR AGS are offered with CNG in select markets. Most CNG cars are sold with manual transmission. Tata Altroz CNG AMT (May 2026, ₹8.70L ex) is the newest and most premium CNG automatic option. For city stop-go use, the lack of automatic in most CNG cars is a real limitation — factor this in if automatic transmission is important
- After buying a CNG car, maintain it correctly: CNG cars require spark plug replacement at 40,000 km (vs 80,000 km for petrol) due to CNG combustion characteristics. Use only NGK BKR6E or manufacturer-specified spark plugs. CNG cylinder hydrostatic testing is required every 3 years by PESO (Petroleum and Explosives Safety Organisation) regulations — budget ₹500–1,000 for this. Don't skip it — it's a legal requirement
Celerio for Maximum Mileage. WagonR for Family Economy. Dzire for Sedan + Economy. Punch for Safe Budget SUV CNG. Altroz for Premium Hatchback CNG. Ertiga for 7-Seat Economy. 41 CNG Cars in India — the Right One Saves ₹3,000–5,000 Every Month.
Rising fuel prices have made CNG cars one of the most practical choices for Indian buyers in 2026. With petrol crossing ₹100 per litre in most metros and CNG offering 30 to 40 per cent lower running costs, more families are switching to factory-fitted CNG models. The most fuel-efficient CNG cars are Maruti Celerio (35.6 km/kg), WagonR (34.05 km/kg), and Dzire (33.73 km/kg). The best CNG car is Dzire by user review — known for mileage and value for money. At 1,500 km monthly city use, a CNG car saves ₹3,000–4,500 per month over equivalent petrol — ₹36,000–54,000 annually. The factory-fitted CNG premium of ₹70,000–1,00,000 pays back in 14–28 months depending on monthly usage. For city daily commuters in CNG-networked cities: factory-fitted CNG is the most rational fuel choice available in India in 2026.
Best CNG car in India (2026) by category: Best mileage: Maruti Suzuki Celerio CNG (35.6 km/kg ARAI, ~₹4.70L ex). Best family hatchback: Maruti WagonR CNG (34.05 km/kg, ~₹5.47L, tall cabin). Best sedan CNG: Maruti Dzire CNG (33.73 km/kg, ~₹6.79L, 5-star BNCAP, best user reviews overall). Best safe budget SUV CNG: Tata Punch CNG (26.99 km/kg, ₹5.70L, 5-star Global NCAP). Best premium hatchback CNG: Tata Altroz iCNG (27.8 km/kg, ~₹7.31L, 5-star GNCAP, only factory CNG premium hatchback). Best compact crossover CNG: Maruti Fronx CNG (28.51 km/kg, ₹6.85L, sunroof). Best 7-seater CNG: Maruti Ertiga CNG (26.11 km/kg, ~₹8.35L). Best safety CNG SUV: Tata Nexon CNG (5-star GNCAP, ~₹8.35L). Overall best value: Maruti Dzire CNG for the combination of high mileage, sedan practicality, 5-star safety, and excellent resale value. If safety is the first priority for a family: Tata Punch CNG (5-star Global NCAP under ₹6L ex) is unique.
Best mileage CNG cars in India (2026): Maruti Suzuki Celerio CNG — 35.6 km/kg ARAI (highest). Maruti Suzuki WagonR CNG — 34.05 km/kg ARAI. Maruti Suzuki Dzire CNG — 33.73 km/kg ARAI. Maruti Suzuki Baleno CNG — 30.61 km/kg ARAI. Maruti Suzuki Swift CNG — approximately 28–30 km/kg. Maruti Fronx CNG — 28.51 km/kg. Tata Altroz iCNG — 27.8 km/kg. Maruti Ertiga CNG — 26.11 km/kg. Tata Punch CNG — 26.99 km/kg. Tata Nexon CNG — 17.44 km/kg (lowest, SUV body). Key note: ARAI mileage is tested under controlled conditions. Real-world city mileage is typically 30–40% lower than ARAI for CNG cars. Celerio real-world city: ~20–24 km/kg. WagonR real-world city: ~20–23 km/kg. Altroz real-world city: 19.80 km/kg (CarWale tested). The Maruti lineup consistently leads on CNG mileage due to lighter body weight and K-series engine efficiency. Tata's iCNG twin-cylinder system is more innovative but delivers lower mileage due to heavier body weight.
CNG vs petrol car in India (2026): CNG wins for: Running cost — CNG at ₹90/kg and 20 km/kg real-world = ₹4.50/km vs petrol at ₹100/L and 14 kmpl = ₹7.14/km. Monthly saving at 1,500 km: ₹3,960. Annual saving: ₹47,520. Environment — CNG burns cleaner, lower particulate emissions than petrol. Petrol wins for: CNG station availability — petrol available everywhere, CNG limited in many cities, towns, and highways. Performance — CNG reduces power output by 5–15% due to lower calorific value. Boot space — CNG cylinder reduces boot space. Refuelling time — CNG filling takes 5–10 min vs petrol 2–3 min. Highway range — CNG tank range is typically 200–300 km (smaller tank by weight constraint) vs petrol 400–500 km. Who should buy CNG: city daily commuters doing 1,500+ km monthly in Delhi, Mumbai, Ahmedabad where CNG network is dense. Running cost saving justifies the ₹70,000–1,00,000 CNG premium within 18–24 months. Who should buy petrol: highway frequent travellers, small-city residents without dense CNG network, buyers for whom boot space is critical, low monthly mileage (under 1,000 km/month — CNG payback takes 3+ years).
Cheapest CNG cars in India (2026): Maruti Suzuki S-Presso CNG — approximately ₹4.62 lakh ex-showroom. Starting price. 1.0L engine, 32.73 km/kg ARAI, tall-boy micro car design. Maruti Suzuki Alto K10 CNG — approximately ₹3.70 lakh ex-showroom. Entry-level, 1.0L, basic features. Maruti Suzuki Celerio CNG — approximately ₹4.70 lakh ex-showroom. Best mileage (35.6 km/kg) at this price point. Tata Tiago iCNG — approximately ₹4.70–8.55 lakh ex-showroom range. 5-star GNCAP, twin-cylinder iCNG. Tata Punch CNG — ₹5.70 lakh ex-showroom. Micro-SUV, 5-star GNCAP, 26.99 km/kg. Maruti Suzuki WagonR CNG — approximately ₹5.47 lakh. Maruti Suzuki Swift CNG — ₹5.79 lakh. For the absolute cheapest factory-fitted CNG with good safety: Tata Tiago iCNG (5-star GNCAP, twin-cylinder) vs Maruti Celerio CNG (best mileage). The ₹4.70L price point with 5-star Global NCAP (Tiago) vs 35.6 km/kg (Celerio) is the core budget CNG buying decision. On running cost alone: Celerio. On safety: Tiago.
CNG automatic cars in India (2026): Yes, but options are limited. Available CNG automatic cars: Tata Altroz iCNG AMT — launched May 2026 at ₹8.70 lakh ex-showroom. The most recent and most premium CNG automatic available. 5-star GNCAP, premium hatchback. Maruti Suzuki WagonR AGS CNG — available in select markets. AGS (Auto Gear Shift) is Maruti's AMT. Maruti Suzuki Celerio AMT CNG — available in select markets. Maruti Suzuki S-Presso AGS CNG — select markets. Not available as CNG automatic: Maruti Swift (MT only), Tata Punch CNG (MT only), Maruti Fronx CNG (MT only), Maruti Brezza CNG (MT only), Maruti Dzire CNG (MT only), Tata Nexon CNG (MT only). The Tata Altroz iCNG AMT is the most compelling CNG automatic — it is the only premium hatchback (Altroz competes with i20, Baleno) with both factory CNG and automatic transmission. For city stop-go buyers who want CNG economy without clutch fatigue: Altroz iCNG AMT at ₹8.70L ex is the best available option in 2026.
CNG car monthly savings calculation (2026): Example: 1,500 km per month, city driving. Petrol car (15 kmpl real-world city, ₹100/L petrol): 1,500 ÷ 15 × 100 = ₹10,000/month. CNG car (20 km/kg real-world city, ₹90/kg CNG): 1,500 ÷ 20 × 90 = ₹6,750/month. Monthly saving: ₹3,250. Annual saving: ₹39,000. At 2,000 km/month: monthly saving ₹4,333. Annual: ₹52,000. At 1,000 km/month: monthly saving ₹2,167. Annual: ₹26,000. CNG premium over equivalent petrol variant: ₹70,000–1,00,000 (varies by model). Payback period: At 1,500 km/month and ₹3,250 saving: 22–31 months (depending on CNG premium). At 2,000 km/month: 14–19 months. At 1,000 km/month: 32–46 months. The saving calculation changes with CNG and petrol price fluctuations. The 2026 numbers assume Delhi CNG at ₹90/kg and petrol at ₹100/L. Real-world savings may be higher or lower depending on your city's CNG price, actual mileage, and driving pattern (city vs highway). CNG cars are unambiguously more economical for high-mileage city commuters — the payback question is how quickly.
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