Explained: The Return of Gasoline

India’s largest automaker is not alone – a host of modifications and innovations that stretch every liter of fuel bring back the petrol variants as the top models among the manufacturers.

The traditional advantage of diesel

Because they use compressed air without a spark plug for the ignition process, diesel engines use 15-20% less fuel than a gasoline-powered vehicle, resulting in lower operating costs in addition to providing higher low-end torque (turning force). This made diesel the first choice for commercial vehicles. However, diesel engines had higher initial costs, and their upkeep and maintenance costs tended to be higher.

While diesel continues to be a more expensive and hotter option among the variants on offer, it is no longer the mileage mainstay for a number of automakers, including Maruti Suzuki. The return to petrol was sparked by tougher BS6 emission standards put in place two years ago and, more importantly, a range of technological changes to deliver the best value for the customer.

Gasoline Technological Innovations

TWO FUEL INJECTORS PER CYLINDER: In Maruti Suzuki’s new DualJet technology, two injectors are placed near the engine’s intake valves, allowing finer fuel atomization, resulting in more complete combustion. The twin jets also help provide smoother, quicker low-throttle responses, a regular feature in city driving conditions.

This leads to cooler running, which allows manufacturers to use a higher compression ratio, which, in turn, helps convert fuel energy into mechanical energy much more efficiently. The combustion chamber used in these engines is more compact, which improves the mixing of fuel and air before ignition, thus providing better efficiency.

The result is a very high mileage of 22-26 kpl under Automotive Research Association of India (ARAI) test conditions. Maruti Suzuki has three new DualJet engines as part of its K-series engine updates which now power the new Celerio, Baleno, Swift, updated Brezza and the S-Cross which was sold earlier .

DualJet, along with Maruti Suzuki’s latest Heartect platform, has ensured that eight of its vehicles feature in the top 10 highest mileage petrol cars, according to a list compiled by Autocar India based on official figures revealed by the manufacturers and/or certified by ARAI.

Models: Suzuki Brezza, Baleno, Celerio

DIRECT PETROL INJECTION: GDI is a sophisticated engine that injects fuel precisely and at very high pressure directly into the engine’s combustion chamber. This leads to higher fuel efficiency, higher power output and significantly lower emissions by overcoming the problem of a compromised combustion rate when fuel and air are mixed in the intake chamber, such as in most traditional vehicles. Hyundai offers a line of turbocharged GDI engines.
Models: Hyundai Creta, Verna, Venue

TURBO GASOLINE ENGINES: Korean and German manufacturers are betting on the “downsizing” of petrol engines, with a turbocharged engine. They are essentially smaller engines, usually with fewer cylinders, which are generally more fuel efficient but low rated. This lack of power is overcome by using a turbocharger – a turbine which is powered by the engine’s exhaust fuel and then feeds this extra compressed air into the combustion chamber, resulting in further combustion of the air-fuel mixture. Result: these small turbocharged engines produce more energy than a larger engine, while consuming less gasoline.

The technology is relatively old – Ford Ecosport’s EcoBoost engine was one of the first engines, followed by the Volkswagen Polo. But both of these cars had low mileage. With the BS6 standards coming into force, Hyundai, Skoda, Mahindra & Mahindra and Tata Motors have all rolled out smaller turbocharged petrol engines of the type used in the Hyundai Venue and VW Taigun. In all these cases, the internal combustion engine has a lower displacement, but not at the expense of power. Maruti Suzuki is an exception, relying entirely on regular naturally aspirated (non-turbo) gasoline engines with its DualJet tuning.

Models: Hyundai Venue, VW Taigun, Skoda Slavia

Hybrid engines

MILD HYBRID TECHNOLOGY: Maruti Suzuki has rolled out mild hybrid technology – or what it calls “Smart Hybrid” – to its premium sedan and utility vehicle models to increase fuel efficiency. The engine automatically stops at idle and starts quietly when optimum conditions are met in both manual and automatic transmissions. It comes with a dual-battery configuration, including a lithium-ion battery, which stores the energy generated during braking to assist the start, stop and torque assist functions of the motor. The energy stored in the lithium-ion battery assists when accelerating.

Models: Suzuki Ertiga, Brezza

STRONG HYBRID TECHNOLOGY: The most powerful Japanese counterweight to the diesel engine, led by the combination Maruti Suzuki India and Toyota Motor, and Honda Motor, focuses on gasoline engines coupled with hybrid systems. Two new Suzuki-Toyota SUVs, the Grand Vitara and the Toyota Hyryder, are powered by gasoline engines with hybrid configurations.

A hybrid system sometimes includes a gasoline engine mated to an electric motor and a lithium-ion or nickel-metal hydride (NiMH) battery that allows the automobile to be pushed in purely electric mode over short distances. The battery is recharged by the motor or through regenerative braking. Maruti Suzuki and Toyota claim that their powerful hybrid SUVs offer fuel efficiency of 27.97 kpl, a claim which however has not yet been certified by ARAI. If the ARAI figure matches the manufacturers’, the Grand Vitara and Hyryder would be the most fuel-efficient SUVs in their segment and among the highest-mileage cars in the country. Honda also claims that its City hybrid will return an average fuel efficiency of 26.5 kpl.

Models: Honda City e:HEV, Toyota Urban Cruiser Hyryder, Suzuki Grand Vitara

Improved transmission technology

Additional speeds allow the motor to run more often at efficient speeds. In the case of its automatic transmissions, Maruti Suzuki has moved from its 4-speed torque converter to a new 6-speed gear configuration.

Continuously Variable Automatic Transmissions (CVTs) have an infinite number of “gears”, providing smooth acceleration and better fuel economy. Dual-clutch transmissions (DCTs), which have two clutches for smooth automated shifting, experience less energy loss than traditional automatic transmissions.

Models: Suzuki XL6 (6-speed torque converter), Hyundai Venue (DCT), Hyundai i20, Toyota Glanza, Suzuki Baleno (CVT gears)