The season was overshadowed by the death of driver Justin Wilson at Pocono, after being struck on the head by debris from Sage Karam's car.

A week after Wilson's fatal accident, the finale was held at Sonoma Raceway, where Scott Dixon secured his fourth career title after a low-key season that saw him win on a tiebreak against Juan Pablo Montoya following his third win of the season after many consistent finishes leading up to the finale.

O  Oval/Speedway R  Road course S  Street circuit BOLD indicates a Fuzzy's Ultra Premium Vodka Triple Crown event.

Apprehension amongst the teams going into the race revolved around the complex, elaborate, and seemingly fragile front wings, and the lack of adequate replacement parts.

Lightning during qualifying in the middle of Round 1B cancelled the entire session, with the grid determined by entrant points, placing Juan Pablo Montoya on pole courtesy of having won the opening race in St. Petersburg.

Montoya led the race early as conditions improved prompting a number of drivers to gamble on a switch to dry tires.

Conditions rapidly improved though and two laps later the leaders pitted for dry tires which promoted James Hinchcliffe into the lead, courtesy of an earlier stop.

Due to this time limit being reached in addition to the cautions, the race ended under yellow following the 3-car crash involving Hunter-Reay, Bourdais, and Pagenaud.

Hélio Castroneves won the pole position with a track record of 1:06.7442, beating Sébastien Bourdais's mark set in Champ Car in 2006.

During the second round of pit stops on lap 55, Dixon was narrowly able to hold the lead, and cruised to victory, his first career win at Long Beach.

With Dixon comfortably out in front, and Castroneves in second, the closing laps focused on a furious four-car battle for third place, led by Juan Pablo Montoya and Simon Pagenaud.

With a second consecutive pole position, Hélio Castroneves took the front row with a time of 1:07.1925 alongside teammate Will Power, while a third-place effort by Simon Pagenaud made it another Penske 1-2-3 qualifying lock-out.

Will Power recovered from a collision exiting the pits (and subsequent drive-through penalty) on lap 24 to come home fourth.

Will Power won the pole position for the second annual Grand Prix of Indianapolis, continuing a dominating trend in 2015 for Penske Racing during qualifying.

In a Three way shootout over the 14 remaining laps with Will Power and Scott Dixon, Juan Pablo Montoya was crowned with his second Indianapolis 500 title.

A southwesterly cold front drenching the circuit for Saturday's race 1 of the Belle Isle Detroit Grand Prix, it was Will Power on pole position.

In a wet race on the composite circuit, Carlos Munoz took his first IndyCar win, lapping through 9th place in the process.

The remnant of yesterday's cold front lingered in a fog over a soaking wet Belle Isle circuit for Sunday's race 2 of the Detroit Grand Prix.

Qualification scrubbed, the grid formed up on the basis of driver points, Juan Pablo Montoya on pole position, with Will Power alongside, row 1.

The driver hasn't gotten his strategy correct, Sébastien Bourdais led to the stripe with 6 laps to go, gapped the field, and earned his first win of the 2015 season, Takuma Sato finished 2nd, Graham Rahal - 3rd.

Under a clear sky, high heat, and 63% humidity, 23 cars took to the D-shaped 1.5 mile Texas Motor Speedway circuit with Will Power on pole position.

With light rain as the field approached for the green flag, starter's orders called for a mandatory single-file rolling start.

Simon Pagenaud won pole position, followed by Hélio Castroneves, Marco Andretti, Ed Carpenter, Juan Montoya and Tony Kanaan.

The second caution didn't fly until 131 when Ryan Briscoe spun and hit his country mate Will Power in turn 4.

Sébastien Bourdais got his first oval win since 2006 and the 34th of his career, tying Al Unser Jr. Hélio Castroneves picked up his 3rd pole at Iowa.

Ed Carpenter got out of his car after the race and confronted the 20 year old rookie driver from Nazareth Pennsylvania Sage Karam.

As debris was strewn from the car, the nosecone section made contact with Justin Wilson's helmet inflicting severe brain damage.

His death marked the first fatality for the Dallara DW12 and the first since Dan Wheldon at Las Vegas Motor Speedway during the IZOD IndyCar World Championship.

Those drivers were Juan Pablo Montoya, Graham Rahal, Scott Dixon, Will Power, Hélio Castroneves, and Josef Newgarden.

Scott Dixon won his 4th championship tying Dario Franchitti, Sébastien Bourdais and Mario Andretti for U.S. open wheel titles.