Dispersed settlement areas (e.g., Slovenia) result in lower development of fixed public transport lines and thereby car-dependent lifestyles. To avoid congestion inside the cities and on highways in these areas, shared mobility modes e.g., carpooling, is one of the effective solutions, increasing the occupancy of personal vehicles. However, passenger pick-up and drop-off locations still remain an important challenge for carpool users and transport officials. As a collection point for carpooling, we can consider “park and pool (P+P)” lots near highways’ interchanges. This study aims to examine the impacts of P+P lots near interchanges on carpooling behavior of users and on improving sustainable mobility on highways in such dispersed settlement areas. To do so, we employed a field survey, incorporated the P+P lots into the mode choice model, and examined different scenarios using the macroscopic transport model. It is found that factors such as travel cost, public transport service limitations, and improved parking facilities impact highway users’ mode choice. Sixty percent of respondents are willing to leave their car in P+P lots near interchanges. The results also show that P+P lots can increase the number of carpool users. It causes remarkable savings in terms of operating and external costs because of the reduction in total distance and time travelled by personal vehicles as well as parking demand reduction in cities. At the moment, especially in Central Europe, it is easier to invest in a “demand reduction” infrastructure than to increase the capacity of infrastructure. Therefore, P+P lots could be a “win-win” situation for both users and operators.