The IndyCar Series for years has longed for American stars who could captivate the audience and raise the excitement level around the slumping open-wheel series.

With Marco Andretti and Graham Rahal in the series, the potential has been there yet neither driver was able to deliver until last year when Rahal became a legitimate title contender.

Rahal won two races — his first victories since his 2008 win on the streets of St. Pete — and he spent the final third of the season thick in the championship hunt.

After a layoff of nearly seven months, IndyCar opens its season Sunday at St. Pete and Rahal believes he is among the title contenders.

"We should be in that conversation," Rahal said Friday. "I have no doubt coming into this season that I can win races. I'd love to help move this series forward. I think there's no doubt that a name, whether it be myself or Marco, would have a great impact on that.

"There's a lot of good, young Americans in this sport. It's exciting times as a whole. There's a lot of guys that can help take this to the next level."

IndyCar had a decent 2015 in which Rahal, Josef Newgarden and Ryan Hunter-Reay combined to win six of the 16 races. The season also came down to a thrilling finish in which Scott Dixon climbed from third in the standings in the season finale to beat Juan Pablo Montoya for the championship on a tie-breaker.

IndyCar goes into 2016 with a deeper lineup than ever.

New to the series this year is American Alexander Rossi, an aspiring Formula One driver who signed a one-year contract with Andretti Herta Autosport. The entry is the fourth under the Andretti banner and came from a late merger with Bryan Herta's single-car team.

Dale Coyne Racing gave American Conor Daly a full-time ride for the first time in his IndyCar career, and he'll be part of the rookie of the year race. Chip Ganassi Racing hired Max Chilton, a British former Formula One driver who has adapted to IndyCar quickly after just a handful of test sessions.

And while Rahal's team is expected to be a one-car team for most of the season, they will run Spencer Pigot, an American who won the Indy Lights title last year, in a handful of races.

KVSH Racing is down to just one full-time entry for Sebastien Bourdais, who won twice last year and wants to be in title contention this year.

Ed Carpenter Racing is also down to just one full-time entry after the partnership with Sarah Fisher and Wink Hartman dissolved during the offseason. Newgarden will run for the championship, and Carpenter will run the oval races.

Schmidt Peterson Motorsport will have its regular lineup with the return of James Hinchcliffe, who missed most of last season after a near-fatal accident in practice for the Indianapolis 500. The team will also use Mikhail Aleshin, who ran for the team in 2014 but was out of IndyCar until last year's season finale.

The championship should be a race between the usual suspects — Dixon, who claimed his fourth title last year, and the Team Penske quartet of Montoya, Helio Castroneves, Will Power and Simon Pagenaud.

Whether Hunter-Reay can be part of that title picture depends on the offseason improvements by Honda to its aero kits. Chevrolet was significantly stronger last year and Honda lobbied for offseason relief to be more competitive.

Although Rahal managed to be strong in a Honda, the Andretti team struggled as it tried to adjust to the manufacturer shortcomings. Honda removed the armadillo-like front wing elements from its 2015 kit in favor of a wing that looks a lot like Chevrolet's. Honda also has a narrower and more curvaceous sidepod profile that also resembles Chevrolet.

Should the changes make the Honda teams more competitive, Hunter-Reay expects to be in the mix.

"Any one of 15 guys win on any given weekend, maybe even more," he said. "There's no weak links on the whole grid. The guy at the very back is going to be less than a second off the leader. I could list seven or eight guys that could contend for (the title). But I think Dixon, Power, that's who you're going to have to look at for consistency.

"It can't just be consistency, though. You got to win races to win the championship. That's what we're all focused on. Really tough to say right now, especially considering we don't know where we are with this (Honda) kit yet."