Carpooling is one solution to help reduce the negative externalities of solo driving. The aim of this study is to analyze the effect of incentives on solo drivers’ intention to carpool. A questionnaire survey was carried out among 1,329 participants, including 590 (38.39%) residents of the Paris metropolitan area who use a car to get to work. Modal choice estimates were modeled using multinomial logit and binomial logit econometric models for car drivers only. First, we analyzed the effect of non-financial incentives, such as nudges and trust in others during the carpooling trip. Second, we analyzed the effect of the combination of nudges with employer subsidies for sustainable mobility on the intention to carpool as a driver or passenger for the home-to-work (or home-to-school) commute. The results show that people aged 18–49, employees, and those with higher levels of education are more receptive to behavioral interventions such as nudges. Applying nudges in isolation is more effective at encouraging carpooling for commuting than combining nudges with employers’ subsidies for sustainable mobility.