Dual-fuel CNG-petrol sedans: Twice the fun, half the cost

Cars like the Maruti SX4 Green (compressed natural gas variant) and the Hyundai Accent CNG actually have many tricks up their sleeves. They can be potent performers in petrol and planet-saving, pocket-friendly easy drivers in CNG mode.

Maruti launched the SX4 Green, the CNG variant of the regular petrol SX4, in August last year, but uptake has been slow. The primary reason has been the availability of CNG, which has now picked up in larger metros such as the NCR region and Mumbai.

maruti suzuki sx4 diesel road test
Photo: The SX4 CNG packs a power-economy 1-2 punch!

CNG sedans combine the best of both worlds. The SX4 CNG still has adequate power when running in CNG mode compared to petrol mode. In CNG mode the SX4 makes 87 bhp of power at 5,600 rpm compared to 104 bhp in petrol mode. Though this drop seems significant, it is hardly felt at city speeds. Even in terms of torque, there’s not much difference. In petrol mode the SX4 puts out 145 Nm of torque at 4,100 rpm and in CNG mode it makes 122 Nm of torque at 4,000 rpm. You may also want to read our SX4 diesel road test

If you look at the fuel efficiency the SX4 Green puts out, it makes it even more attractive. In CNG mode, the car gives about 20 km per Kg of gas. Considering the car can hold about 12 Kg of gas when the pressure is high in the CNG filling stations, it gives the car a range of 240 km on CNG and in addition, the car can hold 50 litres of petrol in its tank. With an average of 12 kmpl on petrol in city conditions, it gives the car a range of 600 km in addition to the CNG, for a total range of nearly 840 km! With such a range one can drive from Delhi to Shimla and back without having to refuel.

The economics get even better when you look at the price of CNG and petrol at the pump. Petrol at nearly Rs. 60 a litre is 100 percent more expensive than CNG at Rs. 29.30 per Kg. That straight away come to Rs. 1.40 per Km on CNG, compared to Rs. 5 per Km on petrol. Considering that the initial price difference between the SX4 VXI (petrol – Rs. 7,05,000 ex-showroom Delhi) and SX4 Green (CNG – Rs.7,55,000 ex-showroom Delhi) is about Rs. 50,000, the savings are huge from day one. If one drives more than 500 km a month in the city, it makes sense to buy the SX4 Green.

However, people have been apprehensive about the longevity of the engine running on CNG. Also read our story on LPG vs CNG

Maruti claims there is no cause for concern, as they have used hardened valve seats, better gaskets and higher grade engine oil, making sure the wear and tear on the engine is minimal. Hyundai too has done the same with the Accent CNG. Also, the way the SX4 CNG functions, helps in engine life. When you start the car in the mornings on a cold start, the engine automatically starts on petrol. It then automatically switches to CNG mode when optimum engine temperature has been reached. This ensures smooth running and engine longevity. There is a manual override switch in the cabin allowing you to drive in auto mode, pure petrol mode or CNG only mode.

Maruti calls this i-GPI technology, with the car being fitted with a dual ECU (engine control unit) – one for gas, and one for petrol. It has separate gas injectors for each cylinder intake, allowing optimum combustion and better performance than CNG kits that are bolted on aftermarket.

The other big concern is on luggage space, because of the huge cylinder fitted in the boot. However, the SX4 CNG can hold about three aircraft cabin baggage sized suitcases in the boot even with the CNG cylinder in place.

If you look at emissions from CNG, they are early 70 percent lower than petrol kilometer for kilometer, allowing you to do your bit for the planet by driving green. The upgraded parts in the engine would mean that the car would actually last longer when driven in petrol mode only.

As for the performance-minded, here’s a car that has the best of both worlds. Want to blast off from the traffic lights or set a quarter mile record? Switch to petrol mode and feel the power. Feeling the pinch on your wallet at the end of the month? Switch to CNG and save that extra cash. Yes, there is a bit of additional weight to lug around, about 70 Kgs or so. But that’s equivalent to having a “healthy” person sitting in the backseat all day long.

Externally, the SX4 Green looks no different from the SX4 VXi. And in petrol mode, it performs exactly like the VXi. As a daily commuter to work and back, the Green therefore makes a lot more sense, if you aren’t likely to haul a lot of extra luggage. If you are looking for a cheaper car with similar characteristics, the Hyundai Accent CNG is priced at Rs. 5.8 lakhs ex-showroom Delhi, and is huge value for money. Of course, it has a dated design and is much smaller compared to the SX4, but a good choice nevertheless.

Go ahead, go green.