The first two races of the season were won by Kevin Cogan (Phoenix) and Michael Andretti (Long Beach), respectively, the first career wins for both drivers on the CART circuit. Rain delayed the Indianapolis 500, postponing it for six days. Bobby Rahal, driving for Truesports, passed Kevin Cogan with two laps to go, and won for car owner Jim Trueman, who was stricken with cancer. Trueman died less than two weeks later.
The season would shape up as a two-man battle between Rahal and Michael Andretti. Andretti won at Milwaukee, which put him in the points lead for the first time. On Father's Day, Andretti was leading on the final lap at Portland. His car ran out of fuel on the final turn of the final lap, and his father Mario beat him to the finish line by 0.07 seconds. It would go down in lore as one of the most shocking finishes in Indy car history, as well as the closest finish in Indy car history on a road course (until 1997).
Rahal was back in victory lane in July, winning the inaugural Molson Indy Toronto, but Michael Andretti still held the points lead. Rahal won four out of five races during a stretch in August and September, and emerged with a 9-point lead in the standings with two races left. Michael Andretti won a key victory at the second-to-last race of the season at Phoenix, while Rahal finished 3rd.
Going into the season finale at Tamiami Park, Rahal held a scant 3-point lead over Andretti. Neither driver was a factor at Miami, and just past the halfway point, Andretti dropped out with a broken halfshaft. Rahal effectively clinched the championship when Andretti dropped out. Roberto Guerrero won the pole and dominated the race, leading the first 111 laps. But on the final lap, his car sputtered and he ran out of fuel. Al Unser, Jr. slipped by to steal the victory, his lone win of 1986. Unser, Jr. won from 19th starting position, the furthest back any driver had won a CART road/street course race at the time.