For 1984, Roberto decided to return to Europe to race F3. Whilst pre-season testing with West Surrey Racing, he got an invitation from Tauranac to join the works Ralt Formula Two team. Moreno finished runner-up to Mike Thackwell, the pair dominated the final European Formula Two Championship, in their Ralt-Hondas. He tasted victory at the Hockenheim and Donington Park races. Tauranac wanted Moreno to stay for the inaugural International Formula 3000 season (1985), but Moreno had been testing the Toleman at the end of 1984, with Senna's car. He look set to get a drive with the team, only to be told that they did not have any tyres, and the deal fell through. A move to Indycars was next for Roberto with Rick Galles's Galles Racing, as he had seen Moreno impress frequently. The deal was for Roberto to drive in the road race. He was invited to do a full campaign in 1986, however they had problems with the car and did not have any good results. When he was unable to find a full-time Indycar drive, he decided to try to get into F3000 driving with Ralt. During that season, he won Gran Premio del Mediterraneo, together with some consistent finishing saw him finished 3rd overall, before receiving the call to join up with AGS.