By now, many of you would be pretty familiar with the standard Chevrolet Optra Magnum prowling our streets. It isn't anything particularly special, nor does it attract much attention, but was the enticing price of CNG that prompted us to give this a try. (ed. note how we said was - although still cheaper than petrol, it has alarmingly skyrocketed to nearly $1.73 per kilo!)

Gassing it

The Optra has a small, square gadget located on the right of the wheel (see above), enabling you to switch between the fuels by pushing it. To do so, you must ensure that the engine revs are ticking over 2000rpm in order to maintain sufficient intake and compression. The orange LED then starts blinking in conjunction with a green light to tell you the system's doing something about it.

Once on gas, you'll get an all green LED display with a row of lamps below the button telling you much you have left. While it takes less than three seconds to accomplish the switch, the car does get caught out sometimes, and a slight jerk is felt accompanied by a noticeable reduction in power. Once that happens, you're high on gas!

While there aren't any numbers on this CNG operator, a simple G-TECH run revealed a 1.3-second gap in 0-100km/h timings. No surprise then, given that CNG yields less power than petrol. Contrary to hearsay, it didn't feel half as bad as one might have thought.



In the 5-speed manual, there was a drop in power above 4500rpm - an engine speed of which the general driving population here will utilize less than twice yearly.

The automatic produced a slightly less punchy midrange and it was slower off the line, almost matching the factory rated acceleration time of 14.3 sec. Overtaking also required a heaver right foot and more engine revs, but we guarantee you will be rendered clueless during daily driving situations.

Number crunching..

On the subject of fuel economy, Chevrolet claims that this 11kg gas tank will do around 180km - that works out to around $19 for a full tank. Assuming that one fills the Optra up with 55-litres of petrol and drives with an economy figure of about 11-kilometres to the litre, a full tank of discounted (eight per cent) RON92 would cost around $106.41, driven over a distance of 605km.

Do the math, and you'll find that 605km on gas costs $63.90 if you were to bother filling it up three to four times - savings far outweigh the slight performance dip. The good news is that CNG generates far less carbon dioxide - about three-quarters of that compared to petrol, and only a quarter in comparable carbon monoxide emissions.
There's more good news - if you're moderately light footed, you might be able to wring up to 210km on a single tank. In fact, we managed Chevrolet's quoted 180km while driving it really hard, and by this, we mean gearshifts at 5000rpm most of the time.

The only wet blanket to Chevrolet's triumph over petrol would be the fact that there are only two effective CNG refueling stations in Singapore - the "GPlus" station under Jalan Buroh's SPC branch, and one other station located along Mandai Link. There isn't much to say about the other branch located in Jurong Island as it is restricted to authorized employees and visitors.

On the whole, we liked the Optra Magnum for its comfort, and despite that heavy CNG tank located in the back, they've done a good job at re-tuning the spring and damper rates of those MacPherson struts (front) and dual linked rears with stabilizer bars on both ends. It could do with bigger wheels, as cornering stability isn't as good as the enthusiast would like it to be.

Aside from being a little noisy above 110km/h, we would rate the car's ride quality right up there with some better Japanese and European 1.6-litre counterparts.

Perhaps what delighted us most was the fact that the steering wheel actually had more than adequate amounts of road feel - bumps and nudges are hinted nicely without being too overpowering for a daily driver such as this.

Although that 109 horsepower, 1.6-litre engine doesn't have a particularly alluring buzz to it, the car will offer you with the essential necessities (in other words, 150Nm of torque) for any other regular commute, which is what most people who purchase this car will be doing anyway.

So on the inside, much of it is similar aside from the bi-fuel switch. Corolla-rivaling levels of rear seat and leg space can be had, while boot space isn't too terribly compromised (see photos). The seats weren't very comfortable, and there were lots of hard, grey plastics that diminished the overall aesthetic appeal. It isn't very pretty on the inside, but nevertheless very functional.

..and more numbers..

For around $59,388, it costs just $1,500 more than the petrol version, much due to the standard "green rebate" for CNG enabled cars. The 24-hour service support and 3-year manufacturer backed warranty should give the general population a little peace of mind that you otherwise wouldn't get in a converted car that would cost you upwards of $3800.

So even if you have a lousy lumbar and the lot, traveling daily in this should put a smile on your face, every single time you pull up at the pumps!