Good afternoon, everyone! My name is Yasuo Nakahara, and I am involved in the planning and development of taxicab models at Toyota Motor Corporation.

        It is a genuine pleasure for me to be here today and make some remarks based on my own experience. I would also like to express our gratitude and congratulations to all concerned on the completion of the trials and HKSAR Government's decision in favor of bringing LPG cabs into Hong Kong.

        As you know, the environment surrounding the automobile is becoming increasingly harsh.

        The problems of the impact of exhaust emissions on the global environment and the depletion of fuel resources are on the verge of working a fundamental change in automobiles.

        In place of the conventional gasoline- and diesel-fueled models, a variety of new models are being proposed and commercialized. The list includes CNG, hybrid, and electric-powered vehicles as well as LPG vehicles.

        Today, I would like to comment on the position of LPG vehicles in this context.

        More specifically, I will make some brief remarks about the features and safety of LPG vehicles, and the particulars of their introduction into Hong Kong.

        This screen shows the number of LPG vehicles on the road in countries around the world. LPG vehicles are also termed as LGV's (Liquid Gas Vehicles). Italy and the Netherlands lead utilization in Europe. In the Netherlands, even the government is putting resources into their development.

        In Japan, the number is not very large, but LPG vehicles are used mainly as taxicabs, which are driven about 100,000 kilometers a year. As such, Japan ranks first in the world for the amount of LPG fuel used by automotive vehicles.

        In Japan, LPG taxicabs are produced at the plants of auto-makers.

        In other words, they are developed and manufactured by the very same companies turning out gasoline vehicles. This is an assurance of high levels of quality.

        In many other countries, LPG vehicles are often products of retrofitting. In respect of quality assurance, we think "original equipment manufactured (OEM)" LPG vehicles are therefore superior.

        Toyota Motor's export of LPG vehicles to Hong Kong features the same high standard of quality as its production for the home market.

        In connection with LPG vehicles, many fear the risk of explosion. In Japan, there were a few cases of explosion with retrofitted models about fifty years ago, but there have been absolutely none since the start of production by original auto-makers. It is true that a few vehicles caught fire due to leakage of fuel in an accident, but this was about as rare as with gasoline vehicles, and there has not been a single instance of fire since the improvements made in 1990.

        At this point, let's take a look at the fuel system of LPG vehicles.

        The fuel is injected into the tank from the inlet on the right side of this screen with the refueling gun after closing the outlet valve and opening the inlet valve. The inlet is equipped with a one-way valve to prevent back-flow. The tank is installed with an automatic valve to keep it from becoming more than 85-percent full. When the re-fueling is completed, the inlet valve is closed and the outlet valve is opened. On the tank outlet and regulator inlet are solenoid valves that automatically close when the engine is off.

        The regulator regulates the fuel change from a liquid to a gas and sends the proper amount to the carburetor. The carburetor produces the optimal mixture of air and fuel.

        This system applies the same methodology as that of the CNG system.

        On the left is a photo of a LPG tank, and on the right, a side-view diagram of the same.

        The items attached to the tank are completely sealed by the semi-container.

        Even in the unlikely event of a leak from these parts, this design ensures that the gas will be expelled through the duct leading outside the vehicle so that none will collect inside.

        This also applies to exhaust from the charging valve indicated by the number 1 in this screen.

        At this point, I would like to mention a few aspects in which the specifications of the LPG vehicles brought into Hong Kong were changed from the domestic Japanese specifications.

        First, in response to the request by the government of Hong Kong, a non-return valve was added in front of the inlet valve on the tank, as shown by the circle in this screen. This was prompted by apprehension about people forgetting to close the inlet valve after filling the tank with LPG.

        This screen shows a socket of a refueling gun on the left top, an Australian-made refueling gun in the center, and the tip and socket of a Japanese-made refueling gun on the bottom.

        The difference lies in the type of coupling between the gun and the socket. Whereas the Australian-made system has a screw-type coupling, the Japanese one uses a quick-coupling device.

        Because Hong Kong had already installed filling-station facilities made in Australia, the sockets on the vehicles were changed to fit them.

        (Upon the start of trial operation of LPG vehicles with Japanese specifications on Hong Kong streets, we recovered parts and examined them with the intention of making adjustments for a better match with driving conditions here. For some parts, we also conducted a review of the kind of material used.)

        Here is a performance comparison of CNG, LPG, gasoline, and diesel vehicles.

        In the aspect of exhaust emissions, gas-fueled CNG and LPG vehicles have the least carbon dioxide and carbon monoxide emissions, while diesel vehicles rank at the bottom for emissions of hydrocarbons, nitrogen oxides, and PM. The cause is the fuel composition in the case of the gas-fueled vehicles and the engine system in that of the diesel vehicles.

        In the aspect of engine performance, gas-fueled engines are inferior to gasoline engines because of the big intake loss due to the fuel mixture in the carburetor. They could, however, deliver a performance on a par with gasoline engines once the gas can be controlled by an injector unit, like gasoline.

        As for cost, CNG vehicles have the worst rating partly because of the small number on the road and the expense of the gas tank, which drive up the cost of the whole vehicle. Cost is their biggest problem.

        Here are the results of a comparison of LPG and diesel vehicle fuel costs, based on vehicle monitoring in Hong Kong.

        As you can see, LPG vehicles are slightly cheaper in terms of Hong Kong dollars per kilometer. Thanks partly to the workings of fuel price policy, they can compete with diesel vehicles on this basis.

        They are also on a par with diesel vehicles as far as maintenance costs are concerned. We have heard that LPG vehicles are also finding favor for their lower levels of vibration and noise.

        Body design of LPG Crown Comfort is more unique and has special cater for taxi application, which you may notice on these pictures.

        In this picture, you may notice that the rear seats are longer, so there is more legroom for the rear seat passengers.

        In this picture, you may notice that the rear door is longer, so that it is easier for the passengers to get on and off the vehicle.

        In this picture, you may notice that the trunk opening in specially designed to allow lower clearance so that it is easier for handling of luggage in and out of the trunk, without having to bend the back too much.

        This screen presents the findings of a slightly more detailed comparison of CNG and LPG vehicles.

        As compared to LPG vehicles, CNG vehicles have a shorter driving range and therefore must have a larger tank. In addition, because of the higher gas pressure, the tank must have thicker steel walls for greater strength, and consequently is heavier.

        These properties would make it difficult to obtain the driving range and trunk space needed for taxi cabs.

        There is also a shortcoming in dependability that should not be overlooked: the wear on engine valve seats is greater than in LPG vehicles.

        This brings me to the tasks for the future.

        As I mentioned a little earlier, LPG vehicles have drawbacks deriving from the fuel control system, which may be equated with that for gasoline-fueled vehicles of a generation ago, because a carburetor is used to throttle the intake and mix it with fuel. This results in great intake loss that worsens the fuel efficiency, and also precludes precision control of the fuel mixture. The conquest of these problems calls for the development of a Multi Port Injection (MPI) system to control fuel using an injector.

        Exhaust emission controls are likely to become even tighter. To cope with this change, it will demand the development of a more stringent LPG fuel control system of this type for taxicabs.

        In closing, I would like to reemphasize three major points.

        First, LPG vehicles offer a high degree of safety, lower level of emissions, and lower operating costs, and they are more suitable for use as taxicabs.

        Second, they have a proven record of use as taxicabs and rate highly for dependability.

        And third, we would definitely like to see LPG vehicles enter into Singapore market and to promote their diffusion throughout Asia, in keeping with our aspiration to contribute to preservation of the global environment and diversification of resources.

        Thank you very much.

Last updated on October 2001
By Transport Department