In the California 8 Hours, a California team tries to beat their new car with their old one.

Three titles are on the line in this year’s Intercontinental GT Challenge, an endurance series of four races that wraps up on Sunday with the grueling California 8 Hours at WeatherTech Raceway Laguna Seca.

Mercedes-AMG leads Audi by a scant nine points for the manufacturers’ crown. Meanwhile Mercedes drivers Rafaelle Marciello and Tristan Vautier hold and 18 point edge over Audi’s Markus Winkelhock and Christopher Haase in the GT3 class.

To make things even more tense, both manufacturers have split the teammates in order to improve—if things go well—the odds that one of their drivers takes the title.

Winkelhock joins Robin Frijns and Dries Vanthoor in the no. 19 Audi. Haas slips into the no. 29 lineup with Kelvin van der Linde and Christopher Mies. Marciello caps the Mercedes no. 43 trio with Maxi Goetz and Lewis Williamson. Finally, Vautier teams with Maxi Buhk and Maro Engel in the 175.

Got all that?

The championship is still to be determined in the GT3 bronze driver class, with Kenny Habul of Mercedes holding a still surmountable lead over Porsche’s Tim Pappas.

While Sunday’s endurance race concludes the Intercontinental GT Challenge, it is also the final race in the Pirelli World Challenge, an 11-race series. And in that competition, K-Pax Racing out of Sonoma is winding up an impressive season, hoping for a second consecutive podium in the California 8 Hours and racing the Bentley Continental GT3 for the final time.

But there’s a twist or two.

Bentley's factory team entered the race and they running their next generation Continental GT3—in its first appearance on American soil—against K-Pax and the rest of the field. The manufacturer will turn the model over to K-Pax for the 2019 season.

That’s right. K-Pax will be battling the car they will introduce next year. It's a race full of intrigue.

“The car looks beautiful,” K-Pax racing program manager Darren Law said of the updated Bentley. “We’ve not had a lot of time with the car, but we’re excited.”

But that's for next year. In the meantime, Bryan Sellers jumps into the K-Pax no. 9 Bentley’s seat, teaming with regular drivers Alvaro Parente and Rodrigo Baptista in the right-hand drive race car to cover the eight hours on its last ride.

It’s Sellers’ first time in the marque. He gained seat time on Thursday during the track's test day for the race. He took VIPs and media around the twisting track on several hot laps in the team's back up car.

“It has been a very successful race car over its lifespan, and we are certainly hoping to send it off on a high note,” Sellers says. “It will be a little bit of a learning curve for me, as I have not had a lot of laps in it.”

K-Pax took the checkered flag in its last two Pirelli World Challenge outings, at Road America and Watkins Glen. The two-car team rarely appears in the endurance series and brought only one car to Laguna Seca.

The car will sport a special livery and support Family House San Francisco, hosting children with pediatric cancer and their families a chance to see the race up close.

And while Mercedes and Audi duke it out for the endurance championship, the guests of K-Pax may also have a chance to celebrate. Last year the team completed 314 laps around the famed 11-turn course over the eight hour span, finishing on the lead lap in third position.

How does one feel after an experience like that?

“Used up,” says Law, who is an endurance veteran as a driver and manager. “It’s grueling. It’s hard work and it’s hot.”

The California 8 Hour rolls off Sunday morning at 9:15am. Practice, qualifying and support races are Friday and Saturday.