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According to some papers, the label fuel economy and the actual fuel economy experienced by the customers may exhibit a gap. One of the reasons may stem from the aerodynamic drag variations due to the natural wind. The fuel consumption is measured through bench test under several driving modes by using the road load as input condition. The road load is measured through the coast down test under less wind ambient conditions as determined by each regulation. The present paper aims to analyze the natural wind conditions encountered by the vehicle on public roads and to operate a comparison between the fuel consumptions and the driving energy. In this paper, the driving energy is calculated by the aerodynamic drag from the natural wind specifications and driving conditions. This driving energy and the fuel consumptions show good correlation. The fuel consumption is obtained from the vehicle Engine control unit(ECU) data.

An electric servo brake system applied for use on electric vehicles was applied for use on plug-in hybrid vehicles in order to achieve fuel-savings together with good brake feel and enhanced operability for plug-in hybrid vehicles. The electric servo brake system is made up of highly accurate braking pressure control that functions cooperatively with regenerative brakes together with a structure in which pedal force is not influenced by braking pressure control. The configuration of these components enabled good braking feel even when the power train was being switched from one drive mode to another. Automated pressurization functions that are intended for plug-in hybrid vehicles and that operate with electric servo brake systems were also developed. These developed functions include stall cooperative control that functions cooperatively with the power train, regenerative coordinate adaptive cruise control, and hill-start assist.

A Sports car's high performance, pursued as its major design point, forces the car to be as light as possible. Because of this, the NSX's body and chassis is build by making the best use of aluminum. This paper describes the development of aluminum for the NSX, and the forming and connecting technologies needed to achieve an all aluminum body.

Several processes, such as casting, forging, and pressing, were used in the manufacturing of the Honda NSX's aluminum chassis. For casting, a high grade method which utilizes program control of mold temperature was developed and put into practical use. For optimum forging, a selection of cold and hot processes were investigated and a process to save energy during processing was pursued. As a result, an overall weight reduction of approximately 50% was achieved.

The Honda NSX, made entirely of aluminum, introduces a concept of using chromium chromate as a method of chemical pretreatment. For other parts that contain a different type of metal, such as various parts of the chassis, a DACRO coating system as well as many other inventions are used. For the paint process itself, a new waterborne basecoat technology is also introduced to obtain a high-class appearance level for the NSX.

The field of diesel combustion research is producing numerous reports on studies of premixed combustion, which promises simultaneous reduction of both NOx and soot, in order to meet increasingly stringent regulations on harmful emissions from automobiles. However, although premixed combustion can simultaneously reduce both NOx and soot, certain issues have been pointed out, including the fact that it emits greater quantities of unburned HC and CO gases and the fact that it limits the operating range. Furthermore, this combustion method sets the ignition delay longer with the aim of promoting the mixing of fuel and air. This raises issues with the product due to the combustion instability and sensitivity to the uneven fuel properties that are found on the market, the capability of the engine response under transient conditions, the deterioration in combustion noise, and so on.

Honda diesel engine vehicles that go on the market in 2018 will be equipped with a newly developed silver (Ag)-type catalyzed diesel particulate filter (cDPF). Ag has high particulate matter (PM) oxidation performance, but conventional catalyst-carrying methods cause weak contact property between PM and Ag; therefore, the newly Ag-type cDPF was developed on the concept of enhancing the property of contact between PM and the catalyst to realize contact property enhancement at the macro, meso, and nano scales. As a result, the newly developed catalyst showed an enhancement of T90 performance by a factor of approximately 2 relative to the conventional Ag-type catalyst in fresh condition. Durability in the environment of an automobile in use was examined through hydrothermal aging, lean-rich (L/R) aging, sulfur (S) poisoning, and ash deposition. The results have confirmed that hydrothermal aging is the greatest factor in deterioration.

A continuously variable valve lift gasoline engine can improve fuel consumption by reducing pumping loss and increase maximum torque by optimizing valve lift and cam phase according to engine speed. In this research, a new control system to simultaneously ensure good driveability and low emissions was developed for this low fuel consumption, high power engine. New suction air management through a master-slave control made it possible to achieve low fuel consumption and good driveability. To regulate the idle speed, a new controller featuring a two-degree-of-freedom sliding-mode algorithm with cooperative control was designed. This controller can improve the stability of idle speed and achieve the idle operation with a lower engine speed. To reduce emissions during cold start condition, an ignition timing control was developed that combine I-P control with a sliding mode control algorithm.

Using sand cores, the weld-able, hollow die-cast parts have been developed. For casting, the transition flow filling method is applied to reduce gas containment and to minimize damages to the core. In designing the products, the newly developed core stress prediction system by melt pressure distribution and the newly developed in-product gas containment prediction system have been applied. The hollow die-cast frame made by the new method attains a 30% increase in rigidity and 1kg reduction of weight.

There has been strong public demand for reduced hazardous exhaust gas emissions and improved fuel economy for automobile engines. In recent years, a number of innovative solutions that lead to a reduction in fuel consumption rate have been developed, including in-cylinder direct injection and lean burn combustion technologies, as well as an engine utilizing a large volume of exhaust gas recirculation (EGR). Furthermore, a homogeneous charge compression ignition (HCCI) engine is under development for actual application. However, one of the issues common to these technologies is less stable combustion, which causes difficulty in engine management. Additionally, it is now mandatory to provide an onboard diagnosis (OBD) system. This requires manufacturers to develop a technology that allows onboard monitoring and control of the combustion state. This paper reports on an innovative combustion diagnostic method using an in-cylinder pressure sensor.

Improvement of engine cycle thermal efficiency is an effective way to increase engine torque and to reduce fuel consumption simultaneously. However, the extent of the improvement is limited by engine knock, which is more evident at low engine speeds when combustion flame propagation is relatively slow. To prevent engine damage due to knock, the spark ignition timing of a gasoline engine is usually controlled by a knock sensor. Therefore, an engine's ignition timing cannot be set freely to achieve best engine performance and fuel economy. Whether ignition timings for a multi-cylinder engine are the same or can be set differently for each cylinder, it is not desirable for each cylinder has big deviation from the median with respect to knock tendency. It is apparent that effective measures to improve engine knock toughness should address both uniformity of all cylinders of a multi-cylinder engine and improvement of median knock toughness.

The International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.

In recent years, increasing attention has been paid to a non-throttling technology that is expected to contribute to a reduction in fuel consumption. This paper describes a study on the technology behind the electromagnetic variable valve timing mechanism (electromagnetic valve mechanism). The electromagnetic valve mechanism ensures highly efficient and stable valve opening/closing control. The detailed information and findings will be described in the main body. In addition, the advantages of the mechanism's application to a homogeneous charge compression ignition engine (HCCI engine) will also be described.

In order to reduce CO2 emissions from automobiles, a highly fuel-efficient hybrid vehicle, the “Insight”, has been developed at Honda. Life cycle CO2 emissions are compared for the aluminum-bodied Insight, a simulated steel-bodied Insight, and a conventional gasoline vehicle. Life cycle CO2 emission is still dominated by the in-use fuel consumption. However, the contribution of CO2 emission from material use and processing could increase when the vehicle fuel consumption is greatly reduced. The use of recycled aluminum reduces CO2 emission from the aluminum-bodied Insight.

This paper introduces a new type of aluminum radiator that has been developed with the objective of high performance and light weight. Aluminum radiators have recently been replacing copper radiators because of their light weight, but the heat rejection of such conventional alminum radiators does not exceed that of copper radiators. Authors established the aluminum radiator not only being light weight but also having high performance through the following approaches. (1) Optimization of radiator core module. (2) Thickness reduction of tube and fin. (3) Development of aluminum alloys with improved corrosion resistance for tubes and fins. As a result, a new type single-row aluminum radiator has achieved 7% higher rejection at 50% lighter weight than those of copper double-row radiator.

Variable-valve-actuation mechanism is considered to be one of the most suitable solutions to realize the compatibility between higher power output and performances in the practical speed range. A new variable-valve-actuation mechanism named “Shuttle Cam” was designed and studied. In this mechanism which was applied to a conventional motorcycle engine with rocker arms and gear-train-driven valve system, the cam gears move along the idler gear. And cam shafts simultaneously slide along the rocker-arm slipper surfaces which are concentric with the idler gear. Consequently valve lift varies continuously in accordance with the alteration in the rocker-arm lever ratio and the cam phasing changes simultaneously in accordance with the cam gear rotation. Result of the experiments has confirmed that the mechanism functions accurately even at high speeds up to 10,000 rpm and some improvements were achieved in power output, fuel consumption, idling quality, and exhaust-noise level.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.

To comply with the environmental demands for CO2 reduction without compromising driving performance, a new 1.0 liter I3 turbocharged gasoline direct injection engine has been developed. This engine is the smallest product in the new Honda VTEC TURBO engine series (1), and it is intended to be used in small to medium-sized passenger car category vehicles, enhancing both fuel economy through downsizing, state-of-the-art friction reduction technologies such as electrically controlled variable displacement oil pump and timing belt in oil system, and also driving performance through turbocharging with an electrically controlled waste gate. This developed engine has many features in common with other VTEC TURBO engines such as the 1.5 liter I4 turbocharged engine (2) (3), which has been introduced already into the market.

This study focuses on improvement of the predictive accuracy of empirical engine models using the Model Base Calibration (MBC) method. This research discusses the effects of the number of measurement points on the accuracy of models for different Design of Experiments (DoE) by using a direct-injection 4-cylinder diesel engine. The results show that the predictive accuracy of the models converges on fixed values when the number of measurement points is increased in Latin Hypercube Sampling (LHS) and D-Optimal Design. This is because the probability density distribution of the measurement data has little variation as the number of measurement points increases. Comparing LHS and D-Optimal indicates that D-Optimal displays a higher level of accuracy, it is able to extend the boundary model because of its greater number of measurement points at the boundaries of the boundary model.

To enable non-throttling operation of gasoline S.I. engine, we have manufactured engines equipped with a newly developed Hydraulic Variable-valve Train (HVT), which can vary its intake-valve closing-timing freely. The air-intake control ability of HVT engine is equivalent to conventional throttling engines. Combustion becomes unstable, however, under non-throttling operation at idling. For the countermeasure, newly designed combustion chamber has been developed. The reduction of pumping loss by the HVT depends on engine speed rather than load, and amounts to about 80 % maximum. A conventional engine-management system is not applicable for non-throttling operation. Therefore, new management system has been developed for load control.