Complex sentence: Back in Belgium he teamed up with Fraikin to compete in rally racing, winning the Rome-Liège Rally and the Coppa d'Oro delle Dolomiti in 1955 driving a Mercedes-Benz 300SL.
Split into simpler sentences: Back in Belgium he teamed up with Fraikin to compete in rally racing. Gendebien and Fraiken triumphed in the Rome-Liège Rally and the Coppa d'Oro delle Dolomiti in 1955 driving a Mercedes-Benz 300SL.