Nowadays the majority of environment problem is pollution of vehicle including the noise of engine combustion. For this reason this thesis aims to compare and study the parameters which affect noise reduction on exhaust pipe. Not only reduce the noise pollution but also maintain the efficiency of the engine. These two substances must be considered. Therefore the researcher emphasized to study the parameters on 3 types of muffler with an equal volume: direct reverse and offset type of mufflers. Initiated by data collection the pressure and the velocity in muffler at the speed of engine at 1000 RPM (slow-running engine mode) and 4000 RPM (maximum running engine mode) were investigated. The data were applied into the program that called “SolidWorks” in order to study parameters. In this step the relation between the pressure and velocity of exhaust were represented. In addition the muffler models were selected to manufacture and test by the standard of The Department of Land Transport. As a result there are two major parameters of the muffler. Firstly the metamorphism of the exhaust gas flow direction pleasurably causes the lower noise at the speed of engine at 1000 RPM. Besides an increase of the flow gas distance can diminish noise at the speed of engine at 4000 RPM as well. However this muffler models were tested under the working mode of catalytic device that is standard equipment for automotive vehicles.

The aim of this research is to study the varieties of weight density distribution affect to the center of mass and vehicle stability. The weight density distribution tester was designed and changed the position of mass. Base on the center of mass is main points of vehicle stability. On the other hand FMCSA standard was applied to field test for considering of the brake performance and vehicle stability. The results of research discovered to the mass distribution on horizontal plane and fixed position Y1 are absolutely influence under an increasing 50 kilograms of mass condition. For the mass distribution on longitudinal plane and fixed position Z2 and Z3 are affected to the increasing of mass 100 and 150 kilograms respectively. Otherwise under an increasing of mass 200 and 250 kilograms there is non-influence to the weight density distribution. In term of the braking performance it’s depends on the lateral mass distribution especially the center position of mass installed on longitudinal and horizontal plane and close up on the front axle (Y2). For the vehicle stability results the position (Y2) is the highest influence for yaw rate and sideslip. Otherwise the position (Y3) or the position of mass installed on longitudinal plane and nearly at the left wheel on the rear axle. Additionally wheel lock-up condition was appeared on the front axle only. Because the behavior of the weight distribution on front axle was decreased lead to mass distribution on longitudinal plane.

Nowadays an automotive industry steadily has been growing and playing a major role on economy development for many years. The crash box is one of the most important parts for safety but it was found that the crash boxes manufactured domestically are not met international standard requirements. This is due to process and material limitation. This process for automotive safety test requires high budget and there is unclear approach for specific test. Therefore a study of crash boxes referred to energy absorption project was conducted as an alternative choice of testing. Regarding to the problems as addressed above this project was aimed to design and test crash boxes which come in various structures; simple type corrugated type and honeycomb type of crash box. In addition it was also emphasized in studying energy absorption behavior and physical deformation of crash boxes after dynamic and static energy being applied. Numeric simulation and static test methodology of front collision were applied for these tests in reference to USA NCAP standard for automobile collision test. Testing all types of crash boxes indicated that the corrugated type was able to absorb energy at 2.8% and 5.9% higher than honeycomb type and rectangular type respectively. This is capable to pick up stress and strain continually and effecting to more energy absorb than another type. Additionally this corrugated structure is feasible and suitable for crash box design in automotive manufacturing.

The objective of this paper was study guidelines for taxation to promote the use of energy efficient passenger cars. The passenger car taxation of 4 developed countries; namely Japan Germany United Kingdom (UK) and United States (US) were analyzed and compared with Thai taxation. And studied barriers for promote the use of energy efficient passenger cars in Thailand. This survey conducted by using the close-ended questionnaires collecting data from 400 people who used passenger cars in Bangkok. The results found that tax on acquisition in the developed countries were only subjected to sales tax while Thailand’s acquisition tax composed of customs duty excise duty municipal tax and value added tax. The ownership tax rates of passenger cars in Japan Germany and UK were based on different fuel consumption parameters such as cylinder capacity vehicle weight and CO2 emissions which can promote energy efficient cars. On the contrary the ownership tax rate of USA and Thailand reduces with the age of vehicle. Fuel tax was imposed to support the country energy policy. Opinion survey results of barriers for promoting energy efficient passenger cars in Thailand showed that the significant problems were the lack of incentives measures to promote the use of energy efficient cars.

Brake system is used the friction between disk and pads. In the driving conditions the brake behavior from the driver is difference. Based on this reason the damage on disk and pads are occurring. Nowadays the ratio of compound materials in pads is several and involved automotive industry has not available enough to experiment. Thus it is difficult to brake pads damaged analyzing in several driving conditions. In this problem the mechanical property tester is main tool for experimental works and test procedure base on the Brake lining and disc brake pads compressibility JIS D 4413. The experiment emphasizes on the flexibility behavior and internal energy by volume with 3 types of brake lining and pads. For the experiment focused on conditions by normal apply brake repeat apply brake and suddenly apply brake. The results revealed the normal apply brake condition the maximum and minimum of flexibility behavior was appeared on brake lining and pads type A and type C with testing temperature at 200C. By the repeat and suddenly apply brake conditions the brake lining and pads type C and type A with 300C is given to the maximum and minimum flexibility behavior. In case of internal energy by volume the maximum and minimum energy was appeared on pads type C and type B at the 30C of testing temperature. For the testing temperature at 200 and 400C the pads type A and type B were got the maximum and minimum energy respectively. On the other hand at the high flexibility behavior is given to high internal energy at the high temperature of the apply brake condition.