For anyone who isn't familiar with some of the names in U.S. racing commentary, I thought I'd give a quick run-down/background on the 2020 D24 Commentators...
Leigh Diffey - (Australia) Leigh made his U.S. debut in 2001, covering CART (now INDYCAR, but not "THEN" Indycar...

). Also covered several other series for Speed Channel (eventually Fox Sports 1) like Speed World Challenge (similar to IMSA Michelin GT), American Le Mans Series, Rolex Grand-Am Cup, and Trans-Am. Starting in 2016, he also covers Formula 1 races for NBC Sports.
Calvin Fish - (England) Rivaled Ayrton Senna in British Formula 3 in the early 80's before coming to the U.S. to compete in various SCCA classes, and IMSA GT, as well as some Indy Lights starts. He won both the 12 Hours of Sebring and the 24 Hours of Daytona in 1990 in the GTO category driving a Lincoln-Mercury (

Had to Google that one, but it
really was "Lincoln-Mercury Motorsports") Cougar. Regularly commentates IMSA races for NBC Sports and Trans-Am races for CBS Sports.
A.J. Allmendinger - (California, U.S.A.) Made his professional driving debut in Champ Car (now INDYCAR, but still not "THEN" Indycar...

) in 2004 before jumping the sinking ship, with his sponsor Red Bull, and joining the NASCAR Cup Series full-time (mostly) 2006-2018. He competed in thirteen 24 Hours of Daytona, always with Michael Shank Racing (a team he part-owns) Lexus or Ford powered Riley Daytona Prototypes (2006-2014), DPi Ligier JS P2's (2015-16), and GTD Acura NSX GT3's (2018-19). He took the overall victory in 2012, finished 2nd twice (2006 & 2018), and 3rd once (2013).
Rick Allen - (Nebraska, U.S.A.) Started working for FOX Sports in 2003, covering the NASCAR Truck Series and the ARCA Racing Series (think iRacing National car) for Speed Channel (Fox Sports 1). He became the lead announcer for "NASCAR on NBC" in 2014 and official cut ties with FOX at the end of the year. He also has taken Leigh Diffey's spot covering "Indycar on NBC" so Leigh could work NBC's coverage of Formula 1.
Paul Tracy - (Ontario, Canada) The "Thrill from West Hill", Paul made his first splash in professional auto racing winning the final Can-Am race in series history in 1986 at Mosport. He was only 17. After working up through the feeder-series, Paul made his IndyCar debut in 1990 and drove full-time until the INDYCAR unification at the end of 2007. He competed in the 24 Hours of Daytona 3 times, 2006, 2007, and 2012, with a best finish of 7th overall (2012).
Townsend Bell - (California, U.S.A.) Another driver who made his profesional debut in CART in 2001-02. He then went to Europe where he became the first American to earn a podium in F3000. He returned to the states to compete in Indycar (Now INDYCAR, then Indy Racing League Indycars) in 2004-2008 and made random Indy 500 appearances until 2016. He won the 2012 12 Hours of Sebring in his very first start in the American Le Mans Series, driving a Lotus GTE car. He made his IMSA Sports Car Championship debut in 2014 driving a GTD Ferrari 458 GT3. He has worked for NBC Sports as a commentator since 2016.
Brian Till - (Texas, U.S.A.) Mostly a club-level driver in the mid-80's, Brian made 20 starts in CART (now INDYCAR) from 1992-95. He then worked for the American Le Mans Series as a pit reporter, and has worked for FOX Sports and NBC Sports. He mostly covers sports car racing, but also covers the NASCAR Truck series and INDYCAR on key dates that overlap with Formula 1.
Krista Voda - (Iowa, U.S.A.) Yes, I am including Krista Voda here SOLELY due to home-state bias, and she shares an Alma Mater with my dad and my sister, having graduated from the University of Northern Iowa.

She started with FOX Sports in 2003 as a NASCAR pit-reporter, as well as a host for a half-hour pre-race show for the NASCAR Truck Series. She has also covered NFL, the MLB World Series, NCAA College Football and Basketball Championships, and the Kentucky Derby. In 2014 she was added as the pre-/post-race host for "NASCAR on NBC". During this year's 24 Hours of Daytona, Krista shared NBC's "Peacock Pit Box" with former NASCAR crew chief Steve Letarte and former NASCAR driver/current "NASCAR on NBC" commentator Dale Earnhardt Jr.