How Maruti Suzuki made the XL6, a big car, so fuel-efficient

Its claimed fuel efficiency of 20.97 km/litre is 34% more than that of Kia India’s Carens (15.7 km/litre).

How Maruti Suzuki made the XL6, a big car, so fuel-efficient

Maruti Suzuki’s New XL6, according to the company, returns a fuel efficiency of 20.97 km/litre, which is amongst the highest for any petrol-powered MPV or SUV in India. In fact, its fuel efficiency is 34% higher than that of Kia India’s Carens, a slightly bigger car, which returns 15.7 km/litre (on the 1,497 cc petrol engine powered model). 

Good fuel efficiency is a function of many things—a car’s aerodynamic body, use of light-weight materials, fuel quality, driving habits, etc—but in the XL6 it’s also due to a lithium-ion battery, and this car is not a hybrid in the conventional sense. 

Unlike Toyota’s Camry or the upcoming Honda City e: HEV which are strong hybrid cars, the XL6 is a mild hybrid (Maruti Suzuki calls it Smart Hybrid). 

Strong hybrid cars use both an electric motor and an internal combustion engine to power the wheels. The XL6 mild-hybrid gets features such as torque assist, brake energy regeneration, idle engine stop-start, and gear-shift indicator. While it doesn’t have an electric motor that powers the wheels, the above technologies lead to decent fuel efficiency improvements. 

CV Raman, chief technology officer, Maruti Suzuki India, told FE that even technology such as automatic idle engine stop-start can give a 2-3% fuel efficiency improvement. “Our Smart Hybrid technology leads to 7-8% better fuel efficiency as compared to a car that doesn’t have these features,” Raman said. 

The company’s Smart Hybrid cars have an Integrated Starter Generator (ISG), which lets the car do three things: 

Brake energy regeneration: The ISG converts the kinetic energy produced from braking and deceleration into electrical energy, and stores it in the battery. This energy is used to restart the engine as well as in torque assist during acceleration. 

Idle stop-start function: It automatically turns off the engine when the engine is idling, i.e. when the engine is on but the vehicle isn’t moving and the driver lets go off the clutch and press the brake pedal. The belt-driven ISG helps in a quicker and silent restart of the engine once the clutch is pressed. This helps in preserving fuel at traffic lights and in slow-moving traffic. 

Torque assist function: Energy that is stored in the battery is used by the ‘motor’ function of the ISG to supplement the engine’s power during acceleration. As a result, the load on the engine is reduced when the car is picking up speed. 

The mild-hybrid technology might have had its share of criticism—the government initially gave this technology tax benefits but later pulled back all benefits— but until we localize power electronics and battery management systems, this technology, according to Maruti Suzuki, makes sense for a market such as India. “The cost and complexity of the tech added to the car is not as path-breaking as that of a strong hybrid, but the fuel-efficiency benefits for the customer are real,” said Raman. 

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