ownership of one or more private vehicles by a large segment of the population
must be accepted. Included are passenger cars, light trucks, small vans, and
multi-purpose vehicles for highway use that are under about 4000 kg in gross
vehicle mass. In addition there are large numbers of motor cycles and in some
countries motor scooters. In
The rate of ownership depends on many factors. The major factor is available personal resources. Indications are that ownership may approach or exceed 0.5 vehicles per adult person. For this reason, motor vehicles on roads and streets is and will be the most important and extensive means of mechanized transportation in rural and urban areas.
The dominance of motor vehicles on roads and streets is strengthened by the efficiency and effectiveness of trucks and busses, especially those with diesel engines. In most urban and many rural areas some form of taxi cab or small for hire passenger vehicle also supplements the personally owned and operated ones.
This means that transport modes which compete with private automobiles must not only provide service cheaper than the incremental cost of driving but also must be at least as fast, convenient and safe as the vehicle which will be displaced. At present in many instances this seems impossible in the context of current trends of urban area development and activity patterns.
Times for trips up to about 200 km are as good or better than trips by air that require motor vehicle connections from airports. For many trip lengths passenger cars are more cost effective when there is a passenger load in addition to the driver. Small diesel powered passenger cars with full passenger loads are the most fuel efficient form of passenger transport available.
Since the mid 1970's passenger car fuel efficiency has doubled. The technology exists to double it again. Further improvements beyond this limit may not be practical. Effective alternatives to petroleum fueled internal combustion engines as the means of on board power have not yet been developed. Work to perfect effective alternative power continues.
No replacement capable of matching or exceeding the present or potential capabilities of self propelled wheeled vehicles i.e. automobiles is in sight. It is in fact difficult to visualize such a device which is not in fact just a refinement of some form of the automobile as it exists today.