His sons' godfathers are fellow Italian Alex Zanardi (Marco) and British Dario Franchitti (Matteo).

Papis is a member of the "brat pack", a group of CART drivers that were close friends off the track, that included Dario Franchitti, Tony Kanaan and the late Greg Moore.

Despite being a race-winner in Formula 3000, he often struggled with the unfamiliar car, and was occasionally outpaced by his much-maligned teammate, Taki Inoue.

He also proved to be an unlucky driver, suffering a spectacular puncture and suspension failure on his début race at Silverstone due to clipping the pit lane wall after a tire change, being left on the grid at Hockenheim due to a transmission failure, and spinning on dust and oil kicked up by David Coulthard at the Ascari Chicane on the first lap of the Italian GP, causing a pile-up and a restart.

In 2001, he won twice and finished sixth overall, but was dropped by the team, mainly due to two collisions with teammate Kenny Bräck.

In 2002, he competed with Sigma Autosport, scoring two third places finishes at Long Beach and Milwaukee, before the team folded due to financial problems.

He mostly concentrated on sportscars since 2001, remarking that "Champ Car needs me more than I need it" as the series struggled to fill its grid for 2003 after many teams defected to the IRL.

He made his debut in Round 3 of the championship driving the No.68 Pontiac, placing 14th overall at Rockingham Motor Speedway.

[7] He made his NASCAR debut in August 2006, competing in the Busch Series race at Watkins Glen International Raceway for McGill Motorsports[8] following the release of Tim Sauter from the ride.

In his first race, at Montreal in the inaugural NAPA 200, Papis avoided Marcos Ambrose' crash (caused by a disqualified Robby Gordon), with 2 laps left, to finish in third place.

In his first Cup season with a dedicated ride, Papis recorded a career best 8th-place finish at Watkins Glen and 15th starting position at Fontana.

At Montreal in the Nationwide Series, Papis drove for Richard Childress Racing and while leading on the final lap, took too much of a last-turn curb, got passed by Boris Said, and recorded a second-place finish.

[9] In 2013 at Road America, Papis, who spent nearly the entire race in the top five, found himself being spun out twice in the waning laps.

Papis also competed in the inaugural Nationwide Children's Hospital 200 at the Mid-Ohio Sports Car Course for Richard Childress Racing, finishing in fourth place.

[12] Finishing 6th in the event, he was slapped following the race by the girlfriend of driver Mike Skeen, who he had crashed with on the final lap, suffering a dislocated jaw.

13 Toyota for Eric McClure at Watkins Glen International, he started 17th and finished 18th after the engine blew.

[15] In 2016, Papis made his debut in Stadium Super Trucks series, running the Honda Indy Toronto rounds in the No.

[18][19] Papis earned the nickname "Mad Max" at the 1996 24 Hours of Daytona during his last stint at the end of the race.