This study was motivated by the case of the disappearance of legal bus services due to
their loss in competition with a kind of car services called “Travel” for the corridor of Padang - Pesisir
Selatan, West Sumatera, Indonesia. Travel might not legal public transport services, and therefore, in
this study is also called un-official public transportation. This study aims to determine the driving
attributes for passenger’s satisfaction of un-official public transportation services and to figure out the
service attributes that need to be improved according to passengers’ perceptions. Data was collected
using random sampling with a total sample of 160 respondents and was analyzed using the Importance Satisfaction Analysis (ISA) method. Quadrant analysis of ISA revealed that the availability of music and air conditioner on-board is not so essential but resulting a higher satisfaction to passengers. Passengers are calling for an improvement of the services by consistently implementing the law against a driver who
uses a mobile phone while driving or driving inconsiderately, and improving the courtesy and friendliness
of the driver
