Spain regulates its intercity bus market by means of a ‘competition for the market’ mechanism, whose design has been modified several times in the last years. This implies that current services are operated under contracts whose conditions are heterogeneous. We take advantage of such fact to empirically measure the impact that regulatory designs may have on fares paid by the users. The results show very large differences between routes whose contracts were awarded under relatively open conditions compared to regionally regulated routes or very old contracts whose concessions were extended and have not been retendered.