Benzine-keuzegedrag van automobilisten

Most gas stations in the Netherlands offer three types of gasoline: Euro (unleaded, low octane grade), Superplus (unleaded, high octane grade), and Super (leaded, high octane grade). Depending on the type of the car, many car drivers can choose between two or three types of gasoline. According to the oil-companies, many car drivers still fuel leaded gasoline, while their car is appropriate for unleaded gasoline. This led the Transportation and Traffic Research Division of the Dutch Ministry of Transport and Public Works to initiate a study of gasoline choice behaviour among car drivers. The aim of this study is three-fold: A: to gain insight into the knowledge and opinions of car drivers about some aspects related to the choice of gasoline, B: to gain insight into the discrepancy between objective and subjective choice sets (types of gasoline), C: to gain insight into the gasoline choice behaviour of car drivers. A sample of about 700 car drivers were asked to fill out a questionnaire, just after refueling their car. The survey was conducted at 10 gas stations in the Randstad region of the Netherlands. Five gas stations were located along a national highway, while the other stations were located within the built-up area of some cities. The results of the survey revealed some differences between car drivers refueling along a highway and car drivers refueling within the built - up area. The observed market shares for the three types of gasoline are about 40% (Euro), 20% (Superplus), and 40% (Super). The main reason for choosing a particular type of gasoline is because the chosen type of gasoline is recommended by the car manufacturer or because respondents think it is the best alternative for their car. It should be noted, however, that many respondents are not well informed about the technical possibilities of their car. Fifty percent of the respondents appeared to be unaware of all types of gasoline that are suitable for their car. This is especially the case for Superplus gasoline (unleaded, high octane grade). Many respondents don't know the price of the chosen gasoline exactly, however, most respondents agree about the most (Super) and least (Euro) expensive type of gasoline. Furthermore, according to the majority of the respondents, Euro gasoline causes less damage to the environment than other types of gasoline. About a quarter of the cars is equipped with a catalytic converter. The main motive for buying such a car was to decrease air pollution by traffic. A notable number of respondents has no knowledge about the expected duration of life and the solidity of catalytic converters. A simple choice model was used to get insight into the fuel choice behaviour of car drivers. Based on the observed choice behaviour of 150 respondents, a multinomial logit model was estimated. The model contained two variables describing the types of gasoline: leaded vs unleaded and octane grade (high vs low). The estimated parameters indicate that the car drivers prefer unleaded to leaded gasoline and (to a less extent) low octane grade to high octane grade gasoline. The model performed well, the discrepancy between predicted and observed market shares was small. Unfortunately, it was impossible to determine the role of prices in the process of decision making, because the price variable appeared to be strongly correlated with the leaded/unleaded and octane grade variables. The preference for unleaded gasoline benefits the environment. Hence, gasoline choice behaviour need not be adjusted. However, it is recommended to improve car drivers' knowledge about the possibilities of their car. Still many car drivers select leaded gasoline because they (incorrectly) suppose that there is no suitable alternative.