Scott Dixon, Ryan Hunter-Reay, and Charlie Kimball

Bolstered by the most-watched Verizon IndyCar Series race ever on NBCSN for the season-ending GoPro Grand Prix of Sonoma, INDYCAR telecasts on ABC and NBCSN posted an overall viewership increase of 16 percent in 2015 that included a 34 percent jump in NBCSN viewership.

The thrilling Aug. 30 race at Sonoma Raceway, won by Scott Dixon to also secure the 2015 Verizon IndyCar Series championship in a tiebreaker over Juan Pablo Montoya, averaged 841,000 viewers on NBCSN, according to The Nielsen Company. Viewership peaked at more than one million in the final full quarter hour. It was the most-watched cable telecast of a Verizon IndyCar Series race since NBCSN acquired the rights in 2009 and the highest cable viewership since the Richmond race on ESPN in 2008.

For the year, combining NBCSN and ABC telecasts, Verizon IndyCar Series races averaged 1.144 million viewers – an increase of 16 percent over 2014. That follows a 19 percent viewership surge in 2014 over the previous year.

Full-season ratings for all Verizon IndyCar Series telecasts improved 15 percent to a 0.76 average in 2015, following a 20 percent upsurge in 2014. NBCSN ratings improved 36 percent to a 0.34 average this season, on the heels of a 32 percent increase last year.

Over the past two years, INDYCAR has increased average TV ratings and viewership by 36 percent and 38 percent, respectively.

"More fans found a lot to like with the Verizon IndyCar Series in 2015 and the growth in television ratings and viewership reflect that," said Mark Miles, CEO of Hulman & Co., parent of INDYCAR and Indianapolis Motor Speedway. "Our TV audiences increased significantly as we approached the championship that went down to the very last lap. As it came down to the wire, motorsports fans were attracted by the thrilling racing and compelling rivalries."

Viewership of NBCSN telecasts averaged 507,000 in 2015, an increase of 34 percent, following a 34 percent rise in 2014. Total viewership on both media partners in 2015 increased from the year before, even with two fewer events.

The Sonoma race telecast showed a 123 percent increase in viewership from the 2014 race and marked the third consecutive NBCSN telecast seen by more than 600,000 viewers, following the Aug. 2 race at Mid-Ohio Sports Car Course and the Aug. 23 event at Pocono Raceway. In fact, the final six NBCSN race broadcasts of the season each yielded more than 500,000 viewers – a number more than the past six seasons on NBCSN combined – and five of those telecasts saw viewership increases of 66 percent or higher from the year before.

The final six races of the season were six of the 10 most-viewed ever on NBCSN. The Mid-Ohio and Sonoma races set a new benchmark and were NBCSN’s two highest-viewed telecasts of the series.

Other key 2015 growth indicators include:

* NBCSN season-long coverage reached 6.409 million unique viewers, the highest total audience ever on the network for the Verizon IndyCar Series and a 47 percent increase from 2014.

* NBCSN viewership among key demographics improved substantially over 2014, with an increase of 32 percent among adults ages 18-49 and a 32 percent rise among adults 25-54.

* Viewership of ABC's broadcast of the Indianapolis 500 Mile Race increased 8 percent over 2014. Full-season viewership of ABC broadcasts improved 1 percent.