In 1999, she moved to the United States, attended advanced racing schools, and drove in the Barber Dodge Pro Series in 2000.

[5] Later in 2000, Duno made her American Le Mans Series debut; she was the first woman to finish in a class podium on this championship.

[5] Beginning in 2004, Duno competed full-time in the Rolex Grand-Am series driving a Pontiac-Riley Daytona Prototype for the Howard-Boss Motorsports team.

For the 2007 24 Hours of Daytona, Duno teamed up with Ryan Dalziel, Darren Manning, and her regular driving partner, Patrick Carpentier; with a second-place finish, Duno became the highest-finishing female in the history of the prestigious race and highest placing Venezuelan driver, eclipsing Ernesto Soto's 5th-place finish in 1982.

While practicing and racing alongside veteran teammate and former Indy 500 winner Buddy Rice, throughout the season, Duno began to show a bit of improvement.

Duno was also among a record number of nine women to participate in ARCA testing in December 2009 at Daytona International Speedway.

[10] On March 4, 2010, it was announced that Duno would return to the IRL IndyCar Series driving for Dale Coyne Racing full–time for the 2010 season.

On Saturday, August 28, 2010, for the first time in history, Duno (along with Danica Patrick, Simona de Silvestro, Ana Beatriz and Sarah Fisher) qualified and ran in an IndyCar Series race that included five women.

Duno made her stock car debut in the ARCA Racing Series' season-opening event at Daytona International Speedway driving the #90 Stringer Motorsports Toyota.

[14][15] Assigned to the #63 Dodge, the announcement was the culmination of several months' work by the team to sign Duno to race in the event.

[19] It was announced on April 14, 2011, that Duno would run the entire 2011 ARCA Racing Series presented by Menards season for Sheltra Motorsports.

Duno was originally awarded the pole position due to qualifying being rained out for the Menards 200 presented by Federated Car Care at Toledo Speedway.

Duno's season was then cut short when her car was officially pulled from the entry list eight minutes before the June 3 practice session for the Messina Wildlife Animal Stopper 150 at Chicagoland Speedway due to Sheltra Motorsports's decision to abruptly cease operations.

[21][22] Milka and Sheltra Motorsports resumed ARCA Series competition with the July 16 Prairie Meadows 200 at Iowa Speedway.

[23] On February 7, 2012, Duno's entry for the Lucas Oil Slick Mist 200 was officially changed from the #63 of Sheltra Motorsports to the #33 of Eddie Sharp Racing.

Duno's season highlights include earning the pole at Talladega Superspeedway and leading the first 11 laps at Daytona International Speedway from her outside row one starting position.

Duno played the role of Kellie "Gearbox", a race car driver, in the live-action-from-animated Warner Brothers movie Speed Racer.

Duno's bilingual kids book, Go, Milka, Go!, depicted her as an animated character teaching the importance of education.

Duno's IndyCar career was controversial;[30] in a number of instances, she was criticized for running too slow and blocking other drivers.

[34] At the Grand Prix of Toronto and at Iowa Speedway in 2010, she was parked by officials due to her lack of speed[31][35] and was subsequently placed on probation by IndyCar for consistently poor performance.

* Season still in progress 1 Ineligible for series points (key) (Bold – Pole position awarded by qualifying time.