The “golden age” of IndyCar racing featured teams and manufacturers able to create their own cars to achieve as much speed as possible.

In a limited way, that era is returning to American open-wheel racing, creating a lot of intrigue for the 2015 IndyCar season.

There’s been a lot of stability among the driver and team roster in recent years, but the long-awaited “aero kits” made their debut in competition Sunday in the season-opener at St. Petersburg.

The Chevy and Honda cars — using new aerodynamic pieces on the front and rear wings to create more downforce, and as a result, speed — have a substantially different look. There are vertical stabilizers on front wings and rear-wing inlets on the Chevys and multiple-stage wings on the Hondas.

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The substantially new cars mean all teams are beginning with a clean sheet and have injected a lot of intrigue and mystery into the IndyCar Series this year.

Chevrolet threw down an early gauntlet, taking the top six spots in Sunday’s season-opening race on the streets of St. Petersburg, but that’s just the start of a five-month, 15-race run through the most diverse array of tracks in motorsports — with six races on ovals ranging in length from .875 to 2.5 miles, five on street courses and five on road courses.

What to look for

Team Penske: As usual, Roger Penske has one of the premier teams in the sport. This year, he has a super-team put together, with four full-time entrants. Defending champion Will Power and three-time Indianapolis 500 winner Helio Castroneves return as the stalwarts in the Penske stable, while former CART champ Juan Pablo Montoya and up-and-coming ace Simon Pagenaud round out the roster. The four took the top four spots in qualifying at St. Pete and finished in the top five. The four drivers combined for seven race wins last year, with Power winning three, Pagenaud two, and Montoya and Castroneves one each. They were four of the top five in the IndyCar standings in 2014. This year’s Penske outfit is reminiscent of the Andretti-Green “superteam” of Tony Kanaan, Dan Wheldon, Bryan Herta and Dario Franchitti 2004-05, when the question was not if an AGR car would win, but which one. AGR won 18 races and finished 1-2 in the championship those years.

The cars: That’s the real story of the 2015 season, besides answering the question “can anybody beat Penske?” With not just horsepower, but also substantial aerodynamic differences between the Chevy and Honda cars — and the Hondas having many different moving and changeable parts — there will be a lot of options and a lot of opportunities for teams to figure things out. What that will also lead to is increased speeds — eventually, possibly, catching up to Arie Luyendyk’s track record of 236 mph at Indianapolis. Another thing that’s notable is that the extra bodywork pieces led to a number of instances of debris on the track and front wing assemblies being replaced in the season opener.

The challengers: While Penske appears to have the super-team, Chip Ganassi Racing and Andretti Autosport also are contending for titles. One of Penske, Andretti or Ganassi’s drivers has won the title every year since 2003. Ganassi is fielding series stalwarts — and former champions and Indy 500 winners — Scott Dixon and Tony Kanaan in addition to veteran American Charlie Kimball. Andretti has a lineup made up of 2012 series champ and defending Indy winner Ryan Hunter-Reay, former Indy runner-up Marco Andretti and 2014 Rookie of the Year Carlos Muñoz. Ganassi, like Penske, is fielding Chevys, while Andretti is carrying the banner for Honda. Also, four-time Champ Car champion Sébastien Bourdais returns to his ride at KV Racing Technology.

A renewal: Graham Rahal and the Rahal Letterman Lanigan team are looking for a renewed season as a revamped one-car team. Rahal is looking for his first IndyCar series win since 2008.

Key races: Again, there will be three consecutive points-paying weekends at Indianapolis, starting with the second annual Grand Prix of Indianapolis on May 9, followed by Indianapolis 500 qualifying May 16 to 17 and the Indianapolis 500 on May 24. The “Triple Crown” of 500-milers will see the other two races get new dates — the race at California moves to June 27, while the 500-miler at Pocono will be the penultimate race of the season on Aug. 23. The season finale will be at Sonoma Raceway on Aug. 30, the series’ first-ever road-course finish. Indy and Sonoma will both award double-points.

Aero kits on ovals: The Indianapolis 500 is the first oval race of the year and the first time the new aero kits will be seen on ovals. With a full week of practice before qualifying, there will likely be a lot of experimentation and fine-tuning. Also, expect speeds to increase at Indy.

What’s new?

New drivers with new teams: Popular driver James Hinchcliffe moves from Andretti Autosport to take over the ride vacated by Pagenaud at Schmidt Peterson Motorsports, a team that won two races last season, and he’ll be joined by James Jakes, who is returning to the series after a strong drive in 2013, replacing Mikhail Aleshin. Tony Kanaan goes from KV Racing Technology to Ganassi. Jack Hawksworth moves to the second full-time car at A.J. Foyt Racing, where he’ll team up with Takuma Sato. Hawksworth had one podium finish last year.

Team merger: Two Indy stalwarts – the teams owned by Ed Carpenter and Sarah Fisher — have merged to form CFH Racing. They’ll field two full-time cars — Josef Newgarden will drive the 67 car, formerly of the Sarah Fisher Hartman Racing stable, and Ed Carpenter and Luca Filippi will share the No. 20 ride, as Carpenter only drives ovals and Filippi will drive the road courses. Carpenter, a former Indy pole-sitter, is always a threat to win on ovals.

The rookies: So far, two rookies are signed up to run the full schedule — Stefano Coletti of KV Racing Technology, and Gabby Chaves at Bryan Herta Autosport. Coletti, who hails from Monaco, had five podium finishes in GP2 last year. Chaves won the Indy Lights title last season.

Who’s not in the field: So far, Ryan Briscoe has yet to land a full-time ride. Mike Conway — who drove road courses only the past two years, last season splitting a ride with Ed Carpenter — also is not yet in the series. Another notable currently without an IndyCar ride is 2014 Grand Prix of Indianapolis pole-sitter Sebastian Saavedra.

New races: The series’ second race will feature the debut at NOLA Motorsports Park in suburban New Orleans on April 12. It will be the first major-series automobile race on the 4-year-old track. They will run on a 2.74-mile, 13-turn configuration on the natural terrain road course. It’s the lone new track on the 14-venue, 16-race schedule this year.

No standing starts: Last year, standing starts were run at races where there were doubleheaders – Detroit, Houston and Toronto (and the Indy road course). This year, there’s only one weekend doubleheader — the post-Indy twinbill at Detroit — and rolling starts will be used at all road and street races.

The 2015 IndyCar season will be intriguing, with a lot of “new” filling in amongst a number of veteran faces. The series’ core of Dixon, Castroneves, Power, Montoya, Hunter-Reay, Bourdais, Andretti, Rahal and Kanaan joins a slew of young, talented drivers, but the manufacturer competition and teams constantly trying to figure out the new chassis parts on a very diverse schedule will make for an entertaining racing season.

IndyCar 2015 Schedule

March 29 — Firestone Grand Prix of St. Petersburg, Fla. (Juan Pablo Montoya winner)

April 12 — Grand Prix of Louisiana, Avondale, La.

April 19 — Toyota Grand Prix of Long Beach, Calif.

April 26 — Honda Indy Grand Prix of Alabama, Birmingham, Ala.

May 9 — Grand Prix of Indianapolis

May 24 — Indianapolis 500

May 30 — Chevrolet Indy Duel (Race 1)

May 31 — Chevrolet Indy Duel (Race 2)

June 6 — Firetsone 600, Fort Worth, Texas

June 14 — Honda Indy Toronto

June 27 — MAVTV 500, Fontana, Calif.

July 12 — ABC Supply Wisconsin 250, West Allis, Wis.

July 18 — Iowa Corn Indy 250, Newton, Iowa

Aug. 2 — Honda Indy 200 at Mid-Ohio, Lexington, Ohio

Aug. 23 — Pocono INDYCAR 500, Long Pond, Pa.

Aug. 30 — GoPro Grand Prix of Sonoma, Calif.