Outpowered by championship rival, John Fitzpatrick in Porsche 935K4, Paul Jr. drove a new Porsche 935 JLP-4 to a debut victory at Brainerd. He scored another win at Portland, before swapping back to the older Porsche for the endurance races. He drove the JLP-3 with his father to win the Mosport 6 Hours. For the next endurance race, Paul was partnered with Mauricio de Narváez, and the pair finished second in Road America, behind the English pairing of Fitzpatrick and David Hobbs. He was re-united with his father at Road Atlanta for the 500 km event. Their last race together resulted in a second place in Pocono. Paul Jr. had clinched the IMSA GT Championship at the age of 22, becoming IMSA's youngest ever GTP champion.