The use of diesel engines in commercial vehicles is still the main choice and the most widely used. The increasing number of commercial vehicles that use diesel engines can pollute the environment and cause noise. In order to reduce exhaust emissions and noise in diesel engines, a particulate filter diesel technology was created which is installed in commercial vehicle diesel engines. This study uses an experimental method. The test was carried out on a Mitsubishi L300 commercial vehicle diesel engine type 4D56 4 cylinder with a cylinder capacity of 2477 cc. The diesel particulate filter technology uses a half honeycomb model made from galvalume plates, with variations in the addition of filters in the form of glass wool of 50 grams, 100 grams, 150 grams, 200 grams, and 250 grams. Testing the exhaust emissions of a diesel engine using a TEN Automotive Equipment Innova 2000 multigas analyzer with a smoketester. Sound noise testing using a sound level meter test tool LT Lutron SL-4001. The test results with the addition of diesel particulate filter technology can reduce exhaust emissions and sound noise. The use of diesel particulate filter technology can reduce exhaust emissions in the form of Particulate Matter (PM) most optimally at the addition of a 100 gram filter with a decrease of 45.9%. The most optimal reduction in noise is the addition of a 50 gram filter with a decrease of 26.5%.

Motorcycles in Indonesia have increased. So, part of the motorcycle increases, especially for brake pads. Asbestos brake pads are prohibited because they have the potential to cause lung cancer. Therefore, alternative brake pads material is needed that are more environmentally friendly. Teak wood powder and rice husk ash are underutilized waste to be used as alternative materials for making brake pads. This research is to determine the characteristics of the mechanical properties of composite materials made from rice husk ash and teak wood powder. The research method used is experimental. The manufacture of brake pads includes mixing materials, pressing, and heating processes. Brake pads are subjected to hardness testing, heat resistance testing, density testing, wear testing, and braking distance testing. The results of this study get the highest hardness test value of 5.821 HV, the highest density of 1.32 gr/cm3, the results of the braking distance test are 4.12 m with a retarding value of 3.67 m/s2, and the wear test results are 2.22 X 10 -6 mm2/kg. Special heat resistance test that meets the SAE J7661 standard with a heat resistance of 3600C for 1 hour.

The important parties must be concerned about Bali's high rate of accidents involving foreigners. One of the likely causes of the collision is the driver's personal component. Due to this, the purpose of this study is to describe the features of traffic accidents involving foreigners and determine the most effective safety measures to reduce such incidents. A quantitative descriptive method is used in this investigation. Simple random sampling with 90 respondents was the sampling strategy employed in this study. In-depth interviews and questionnaires were also used as data collection techniques. The findings indicated that some characteristics, such as drunk driving, going over the speed limit, infrastructure, running red lights, and operating a motor vehicle on icy roads when it is raining, are the main causes of traffic accidents involving foreign people. Furthermore, there were three approaches to traffic safety management according to respondents from the highest to the lowest percentage. The highest was traffic engineering (42%), education and training (30%), and law enforcement (28%).

The use of rear spoilers on MPV vehicles is often used by the public to get an aerodynamic vehicle body design. The understanding of the function of using rear spoiler accessories in the community is still low, so it is necessary to study the characteristics of air flow in aerodynamics. This study aims to determine the flow characteristics of MPV type vehicles with standard and longer rear spoiler installation. This research was conducted in a Subsonic Open Circuit wind tunnel with test section dimensions (365 x 365 x 1250) mm. The flow characteristics were observed experimentally that passed through the model surface resembling the first generation Toyota Avanza MPV with a ratio of 1:20 with variations of the standard and longer rear spoiler installation. Measurement of the flow velocity profile behind the vehicle test model was carried out at an X/L ratio of 0.32 from the leading edge with a speed adjusted to the Reynolds number value of 1.96 x 105. The flow characteristic observed was the pressure distribution (Cp) on the center line of the top surface. and under the test vehicle model, the flow momentum deficit behind the test vehicle model, the lift pressure coefficient (CLP), and the drag pressure coefficient (CDP). The results of data collection show that the installation of a standard and longer rear spoiler relatively increases the Cp value, the flow momentum deficit behind the vehicle model, the lift pressure coefficient (CLP) value and decreases the drag pressure coefficient (CDP) value. The biggest increase was in the installation of a longer rear spoiler with an increase in the Cp value of 4.7%, an increase in the flow momentum deficit by 1.27%, an increase in the CLP value by 0.11% and a decrease in the CDP value by 0.06% compared to the vehicle model without using a rear spoiler.

This paper examines how vehicle service companies in Bali have implemented their work and operational requirements. This study aims to find out whether vehicle service providers have implemented Standard Operating Procedures for tourists in Bali. This research is a descriptive research. The sample in this study were 42 service providers spread across the island of Bali.  The data collection methods was simple random sampling while the data analysis using content analysis. According to the authors' data, only 18 (43%) of the companies that provided motor vehicle rental services had operational standards (SOP), while the other 24 (57%) either lacked them or couldn't prove they existed. 18 or more of these service providers, many of which merely verbally convey it. Other than that, there is still a gap between the work done by the 18 service providers and what is done in practice, such as when permits are issued to foreigners who lack an international license, carry a false identity, or give a permissions to Underage foreigners. There is no legal framework that regulates the SOP for vehicle rental. So that makes the existing SOP very diverse. The legal framework regarding standardization of policies, regulatory requirements for motor vehicle leasing should be regulated by one of the policy makers, in this case the government.