In September 2017, Alonso told the McLaren chief executive offer Zak Brown he wanted to drive in the 2018 24 Hours of Daytona as preparation for the 24 Hours of Le Mans. Brown agreed to the idea and assigned Alonso to drive for United Autosports. Alonso entered the race because he sought a different challenge and spoke to García on what to expect. He drove a Ligier JS P217 in a test session at the Ciudad del Motor de Aragón on 21 November and driver Filipe Albuquerque advised him. Alonso, the sports car entrant Philip Hanson and McLaren's reserve driver Lando Norris qualified 13th and finished 38th after multiple mechanical issues affected the car during the race. Alonso returned to race in the 2019 24 Hours of Daytona with Wayne Taylor Racing. He shared a Cadillac DPi-V.R with Kamui Kobayashi, Renger van der Zande and Jordan Taylor; the quartet completed 593 laps to win the rain-shortened event.