## 1 Introduction  
Currently, urban transport systems are using more and more intelligent solutions based on the use of a smartphone to provide access to the service. This kind of trend refers to the idea of Mobility as a Service, called MaaS. MaaS describes a shift away from personally owned modes of transportation and towards mobility provided as a service. One of the solutions more and more commonly chosen by individual users is car-sharing systems.  
The car-sharing system is a model complementing the public transport service. It is based on the short-term rental of cars offered by operators in selected areas--mostly in cities. Its concept is similar to that of typical car rentals, with the difference being that cars can be rented for less than an hour [1; 2; 3]. According to that principle, car-sharing is regarded as an alternative to having one's own vehicle with secured availability and maintenance [4; 5].  
There are three main types of car-sharing systems: round-trip car-sharing systems, one-way car-sharing systems, and free-floating [6; 7; 8; 9; 10]. The main difference between the types of systems is in the vehicle location and vehicle return policy. The diversity of car-sharing systems is presented in Figure 1.  
Since May 2019, car-sharing services have been offered in 3128 cities, in 59 countries, which represents 30% of the entire world [11]. There are currently 236 operators in the world [11]. The most popular service model is the one-way car-sharing currently operating in 51 countries [11]. Free-floating car-sharing system, in turn, operates in 36 countries around the world [11].  
Currently, the fleet of vehicles available in car-sharing systems mainly comprises conventional cars. However, hybrid and electric vehicles are gradually being implemented. It would seem that according to the assumptions of car-sharing as providing rental vehicles in cities, it should be based on small city cars that can be easily parked in a small parking space [9; 12]. However, scientific studies conducted on a fleet of 187 vehicles from 40 car-sharing systems operating in 25 European countries showed that mainly C-class vehicles predominate [13]. That class is a lower, medium type of passenger car, called compact cars, with a compact design ensuring relative driving comfort for four adults and moderately large luggage space [13].  
Because the current trend is the use of increasingly technologically advanced vehicles that will be able to adapt to intelligent transport systems, and furthermore, due to the fact of growing interest in replacing traditional vehicles with autonomous ones, we decided to question the possibility of using autonomous vehicles in intelligent systems. In this article, we present our method of appropriate fleet selection based on the Delphi method and calculations made through a scientific experiment performed based on [PERSON]'s plan. The results indicate the relation of travel parameters (including vehicle type) to the total cost of travel in urban transport systems. We also present the main terms related to autonomous vehicles. This article provides support for people who want to deepen knowledge about autonomous vehicles and new mobility solutions used in urban transport systems.