Modern racing technology meets historic horsepower as the Historic Trans Am Series joins the on-track lineup for the Grand Prix of Sonoma Verizon IndyCar Series season finale at Sonoma Raceway on Sept. 14-16. The Formula Car Challenge Series and IMSA Porsche GT3 Cup Challenge round out the weekend schedule.

A 24-car field of Historic Trans Am muscle cars, including Mustangs, Camaros, Javelins, Firebirds and Cougars will hit the track for races on Saturday (2:15 p.m.) and Sunday (1:30 p.m.). These are real Trans Am race cars — not reproductions — racing and competing 50 years after the series’ heyday in the late 1960s and early ’70s.

The cars, including a 1968 Sunoco Camaro originally driven by Mark Donohue and a 1970 Dodge Challenger driven by Sam Posey, have been restored to their original condition and are raced hard by drivers dedicated to honoring the history of this iconic series. Fans can get an up-close look at these machines at a display in the main paddock throughout the weekend, as well as a Grid Walk on Sunday morning at 10:30 a.m.

This marks the second time this year the Historic Trans Am Series will join a Verizon IndyCar Series race weekend. The two series hit the streets of Long Beach in April at the Toyota Grand Prix of Long Beach, but this will be the first time the pairing is on track in Sonoma.

The Porsche GT3 Cup Challenge USA by Yokohama returns to Sonoma for the second consecutive year. The IMSA-sanctioned series is one of the largest of Porsche’s 21 single-make Cup Challenge series in the world.

Both young aspiring drivers and veteran semi-pros have a home in this series, which uses the iconic Porsche 911 GT3 Cup car. Racing in the Porsche GT3 Cup Challenge USA by Yokohama is divided into two classes — Platinum Cup, featuring 2017 and 2018 Porsche 911 GT3 Cup cars, and Gold Cup, which is comprised of the previous iteration of the race car. The Porsches will hit the track for main events on Saturday (1 p.m.) and Sunday (12:15 p.m.).

The weekend will also feature open-wheel racing in three classes of the Formula Car Challenge presented by Goodyear series. This marks the seventh time the series joins the Verizon IndyCar Series weekend in Sonoma. The 14-race series features three classes of spec cars on track at the same time, each competing for points and championships within their respective classes. More than 30 cars have taken the green flag in past events, making this one of the largest open-wheel races in the country.

The headliner of the weekend is the Verizon IndyCar Series, which crowns its champion following the 85-lap INDYCAR Grand Prix of Sonoma on Sunday. The series championship has come down to the final race since 2006, including last year when Team Penske’s Josef Newgarden claimed his first Verizon IndyCar Series championship.

This marks the fourth consecutive year the open-wheel series will conclude its season on the 12-turn road course, as well as the end of a 14-year run in the Sonoma Valley, as the series moves away from Sonoma in 2019.