Car beats factory figures

The latest fourth-generation Suzuki Swift has proved to be a “real petrol saver” in an independent fuel-economy test conducted on North Island roads.

A 1.2-litre petrol-electric GLS CVT automatic clocked up an average fuel consumption of 3.3l/100km over a mixture of motorway, rural open roads and built-up city streets.

That amounted to a 23 per cent improvement over the official factory figure of 4.3l/100km on the 3P-WLTP test cycle.

The petrol-electric Swift GLS manual gearbox version did even better with an average of 3l/100km in local fuel testing – 25 per cent more frugal than its factory figure of 4l/100 km.

All this equates to a driving range of 1,233km for the manual GLS Swift and 1,121km for the GLS automatic based on the standard 37-litre fuel tank.

Both tests were carried out by Donn Anderson. He has been involved in fuel-economy events for more than 30 years and has driven record-breaking runs in the UK and New Zealand. 

He says: “While the average driver may not achieve these outstanding driving ranges on a tank of fuel, it does demonstrate how remarkably economical the vehicle can be when driven moderately and with care.

The latest Swift boasts a relatively high compression ratio of 13.9:1 and better thermal efficiency than the previous four-cylinder equivalent with an identical capacity of 1,197cu cm. The power unit with variable-valve technology and four valves per cylinder has fewer components, is lighter and has reduced friction losses. All this contributed to “outstanding” fuel economy.

The test route, which began and ended in Auckland, encountered heavy traffic and roadwork disruptions that meant frequent stop-start driving. When these hold-ups were encountered, the Swift’s engine shut down and restarted automatically, which proved to be a useful advantage.

Suzuki’s integrated starter generator (ISG), which replaces a conventional alternator, reduces fuel consumption by providing supplementary motor power for up to half a minute. The ISG uses the energy of deceleration to generate electricity for charging the lead-acid battery and the lithium-ion battery.

It also functions both as a generator and electric motor to restart the engine, and provide electric-motor assistance during acceleration. The ISG monitors brake-pedal depression during deceleration to maximise regeneration levels.

“The engine stopping and restarting is almost imperceptible,” says Anderson. “Restarting is via a belt drive system that eliminates gear noise produced by conventional starter motors. Occupants are usually unaware the motor has stopped and then restarted.”

Anderson concentrated on decelerating as much as possible to conserve fuel, and found the new, larger information screen a valuable asset in reducing fuel consumption. Within the cluster a symbol illuminates when the lithium-ion battery is charging during deceleration. The central-mounted screen details average and instant fuel consumption, and fuel-economy history.

He says: “Increased low-speed torque and enhanced combustion assist in the easy-going nature of the engine in the latest generation Swift.”

The new CVT in the latest model is lighter and more compact than its predecessor with an infinite number of possible ratios available. It proved flexible on the fuel-economy run, displaying an ability to cruise at 100kph with the engine turning at little more than 2,000rpm.

Anderson notes the performance of the five-speed manual gearbox as highly creditable. “There are now so few manual transmission cars available, but the GLS manual is a fine exception with its refined gearbox that’s quiet and easy to use with its light action. The 3l/100km achieved is exceptional result for a mild hybrid and confirms there’s still a place for the manual gearbox.”

While using less fuel, the new Swift range is also cleaner running with lower carbon-dioxide emissions with the official 96gCO2/km CO2 result for the GLS CVT 9.4 per cent lower than the outgoing third-generation non-hybrid. 

The Swift is New Zealand’s most affordable hybrid priced from $25,990 on-road costs. The CVT auto range starts at $27,500 on its current promotion.