Daihatsu Develops e:S Technology for 30 km/l in JC08 Mode

Jul. 19, 2011

DAIHATSU MOTOR CO., LTD. (Daihatsu) announces its development of a high fuel efficiency technology that will be at the heart of production of future motor vehicles with high fuel efficiency, low prices, and resource-saving features. The technology is branded "e:S Technology," which stands for Energy Saving Technology.
In the process of this development, Daihatsu carried out exhaustive overhauls of existing technologies, including all aspects of the engine, the transmission, and the body structure, to maximize energy efficiency and achieve almost a 40% increase in fuel efficiency.*1
This technology will be introduced to a new fuel-efficient vehicle model due to be released in September this year. It is anticipated that it will be the only gasoline powered vehicle*2 with a fuel mileage of 30 kilometers per liter in JC08 mode. This new mini vehicle will be marketed as the third environmentally friendly car that is accessible to everyone, featuring high fuel economy, energy conservation and an entry price of less than 800,000 yen.

Main Features of e:S Technology

1. Power Train Evolution

  • A new engine with maximized combustion efficiency and minimized energy loss
  • Continuously variable transmission (CVT) with higher power transmission efficiency

2. Vehicle Evolution

  • Shell body streamlined to achieve a weight reduction of around 60 kg*3
  • Air resistance, rolling resistance and other running resistance lowered
  • Thermal management in the engine room

3. Energy Management

  • A new Eco-Idle system with pre-stop idle reduction functions
  • Eco power generation control (with regenerative braking functions)

*1: Source: Daihatsu; Comparison with the Mira 2WD/CVT without idle reduction functions
*2: Source: Daihatsu; As of July 2011, excluding hybrid-powered vehicles
*3: Source: Daihatsu; Comparison with the Mira 2WD/CVT with idle reduction functions

Technical Overview

1. Power Train Evolution

A new engine with maximized combustion efficiency and minimized energy loss

  • Combustion efficiency has been boosted by achieving eight improvements, including an enhancement in the compression ratio from 10.8 to 11.3 and the downsizing of the particles sprayed from the injector.
  • An i-EGR system has been utilized. It applies the ion current combustion control, in which ions in the combustion chamber are used to identify the state of combustion, to EGR control. Through close control according to engine characteristics, EGR gas is fed in larger quantities to massively reduce the pumping loss.
  • Mechanical loss has been minimized by combining 11 improvements, including a reduction in chain tension by cutting the chain width, a tension reduction in the piston rings and modification of the oil seal.
  • An electronic throttle body made of a lightweight resin has been utilized. Coordinated control of the engine and the CVT using the electronic throttle is performed precisely according to the speed range to maintain a state of the highest efficiency, irrespective of the gear ratio in the CVT.

Continuously variable transmission (CVT) with higher power transmission efficiency

  • Power transmission efficiency has been increased by combining eight improvements, including utilizing a high efficiency oil pump and lowering the CVT control pressure.
  • The engine load has been lowered by optimizing the transmission gear ratio on the basis of increased power transmission efficiency, reduced running resistance and vehicle weight cuts.

2. Vehicle Evolution

Shell body streamlined to achieve weight reduction of around 60 kg*

  • The shell body has been streamlined without impairing the body rigidity necessary for safety and onboard comfort. This has achieved a weight reduction of approximately 30 kg* while maintaining vehicle length.


  1. Revision to the layout of the frame components

  2. As many components as possible have been made straight in form to reduce reinforcements.

  3. Effective layout of high tensile strength steel plates

  • Weight reduction is achieved by exhaustively redesigning every single interior part. For example, a new structure sheet frame is utilized and the thickness of the instrument panel and door trims is reduced.
  • The weight of the CVT unit for idle reduction is slashed by utilizing a thinner-walled CVT case, an aluminum oil pump cover and an aluminum planetary carrier, and by introducing integrated molding for the secondary sensing gear and the piston.

* Source: Daihatsu; Comparison with the Mira 2WD/CVT with idle reduction functions

Running resistance lowered

  • Rolling resistance has been lowered by utilizing low rolling resistance tires with new tread rubber, and by enhancing the drive parts.
  • A CAE simulation and a wind tunnel test were conducted in the design phase to improve the forms of the front corners and slow the underfloor flow. Air resistance has thus been reduced.

Thermal management in the engine room

  • The layout of the bumper openings and air cleaner ducts has been optimized and the air flow route has been improved to implement thermal management and lower the temperature of the intake air into the engine. A decline in air intake volume resulting from volume expansion of the intake air is suppressed to boost the engine combustion efficiency.

3. Energy Management

A new Eco-Idle system with pre-stop idle reduction function

  • The new car will be the world's first CVT vehicle equipped with the pre-stop idle reduction function. It applies a brake and stops the engine when the vehicle speed is 7 km/h or less to increase the idle reduction duration and improve fuel efficiency.
  • Dedicated components for idle reduction systems have been decreased to achieve weight and size reductions.


  1. An ECU for the CVT has been incorporated into the idle reduction computer integrated with auxiliary power supply to prevent the navigation system from being reset upon engine restart.

  2. A CVT without a motor-driven oil pump has been introduced.

  3. A brake unit with a built-in hill start system has been introduced.


Eco power generation control (with regenerative braking functions) to gain maximum benefit from kinetic energy at the time of slowdown

  • The function of converting the kinetic energy of the slowing vehicle into electric energy with an alternator and feeding it back into the battery has been enhanced. The power output of the alternator at the time of vehicle slowdown has been increased and the charge acceptance properties of the battery have been improved to substantially cut power generation from the alternator at the time of normal operation and acceleration, and to reduce the burden on the engine.
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