Motorsports Formula One and IndyCar In November 2012,
NBC Sports announced that Diffey would join its network to become the play-by-play announcer for its broadcasts of both
Formula One and
IndyCar events starting in 2013. Diffey called the day of the announcement "one of the best days of my life. People have been so complimentary." In December 2015, Diffey, Hobbs and Matchett were given an Honorable Mention in a list of Best Broadcast Teams of the year published on the
Sports Illustrated website SI.com. On two occasions, Diffey covered both series on the same day. On 23 August 2015, he called the
Belgian Grand Prix from NBC's base in Stamford, Connecticut, before he and Matchett traveled to
Pocono Raceway for the
ABC Supply 500. Likewise, on 3 September 2017, Diffey called the
Italian Grand Prix in Connecticut and then traveled to
Watkins Glen International for the
IndyCar Grand Prix at The Glen. Diffey's open-wheel focus shifted solely to IndyCar in 2018 when the US Formula One television rights were transferred to
ESPN, and they chose to take commentary from
Sky Sports instead of making their own.
NASCAR Diffey was one of several recurring co-hosts of
NASCAR America, a weekday
NBCSN program dedicated to NASCAR. While he had covered NASCAR practice and qualifying sessions with Speed, After calling the race, Diffey spoke of the experience as "a thrill...I've been a NASCAR fan and dabbled in it, and for that to be my first race was something else." Dover, and Kansas NXS races. Diffey made his
Sprint Cup Series broadcasting debut alongside
Dale Jarrett at
Homestead-Miami Speedway in 2015, leading NBCSN's "Hot Pass" coverage of NASCAR's championship race, which focused solely on the four drivers still eligible for the series championship. Diffey reprised this role with
Parker Kligerman in the 2016 Homestead race, and again with Jarrett in 2017, 2018, and 2019. In August 2017, Diffey served as the lead announcer for
NASCAR on NBCs primary coverage of the renamed
Monster Energy Cup Series for two races (the
I Love New York 355 at The Glen and the
Pure Michigan 400), filling in for regular announcer
Rick Allen who was working in London with NBC's coverage of the
2017 IAAF World Championships. On 13 March 2024, it was reported that Diffey would replace Allen in NBC's NASCAR Cup Series booth shortly after the
2024 Summer Olympics.
The Indianapolis Star reported on 8 August that Diffey's first race would be the
Coke Zero Sugar 400 at
Daytona International Speedway. Diffey was officially confirmed by NBC on 20 August as the network's new play-by-play voice for the Cup Series. Consequently, Kevin Lee filled in for him in the IndyCar booth for the rest of the year.
IMSA Diffey returned to sports car racing in 2019 as the lead announcer for NBC Sports' coverage of IMSA's
WeatherTech SportsCar Championship, beginning with the
2019 24 Hours of Daytona.
Motorcycles Diffey began calling the
AMA Supercross Championship in 2020, working play-by-play for NBC for the series along with
Ralph Sheheen. Diffey took over the lead commentating role replacing Sheheen starting the 2021 season with
Ricky Carmichael, Daniel Blair, and Will Christien. He also served as a studio host for the network's
MotoGP and Moto2 coverage.
Global Rallycross Diffey served as lead announcer for several events of NBCSN's coverage of
Red Bull Global Rallycross beginning with the opening event from Fort Lauderdale in the
2015 season. He continued to cover the series for the network until the series folded, doing play-by-play for the final round of the
2017 season from the Port of Los Angeles on 14 October.
Dakar Rally Diffey served as the US announcer for the daily world feed highlight broadcast of the
Dakar Rally on NBCSN.
Other ventures Diffey has worked on NBC's coverage of the
Olympic Games, covering
luge,
skeleton, and
bobsled at the
2014 Winter Games in Sochi. NBC executive Sam Flood had expressed interest in having him serve as an announcer outside of motorsports while negotiating his contract with the network, and he prepared Diffey for the Olympics by having him host the
Penn Relays and the
Luge World Cup. Beyond the Olympics, Diffey has covered rugby, anchoring studio coverage of
Premiership Rugby and doing play-by-play for the
Collegiate Rugby Championship. He also covered the
Prefontaine Classic in 2018, as well as the
2019 World Athletics Championships. In 2021, Diffey took over as the NBC track and field commentator, covering both the US Olympic trials and the
2020 Summer Olympics. At the 2024 Summer Olympics in Paris, Diffey botched the call of the
men's 100 metre final, hastily declaring Jamaican
Kishane Thompson the winner in a photo finish which found American sprinter
Noah Lyles officially winning the gold medal. Diffey took responsibility for the mistake in a social media post the following day, saying, "My eyes [and] instinct told me Kishane Thompson won. Obviously, that wasn't the case. I shouldn't have been so bold to call it, but I genuinely thought he won. I got it wrong." Diffey makes a cameo in the movie
F1 (2025), providing commentary for the film's opening scene at the
24 Hours of Daytona. == Personal life ==