Updated

NBC Sports Network said Tuesday its coverage of the IndyCar Series at Long Beach is up 45 percent in both the national ratings and its number of viewers.

The cable channel had 468,000 viewers and a .32 national rating for Sunday's race at Long Beach. That's up from 323,000 viewers and the .22 rating from the same race in 2011.

It was a welcome climb for NBC Sports, which scored a .25 for the April 1 race at Barber in the network's first race of the season. The debut broadcast ran head-to-head with a compelling NASCAR race on Fox.

Through two races this season, NBC Sports' numbers are up 9 percent in both ratings and viewers from the same two races last year.

"After growing our IZOD IndyCar viewership by double digits each of the last two seasons, we are very pleased to be attracting more viewers again this year through two races," said Jon Miller, president of programming for NBC Sports Network.

"We are grateful that the hard work and commitment by our production, marketing and promotional staffs continues to pay dividends. IndyCar fans are the true beneficiaries."

IndyCar, meanwhile, was proud of the .46 coverage area rating that NBC Sports scored from Long Beach. The network does not use coverage ratings, which measure viewership in homes that have the cable channel, and instead focuses on the true national rating and actual number of viewers.

In comparison, cable channel Speed uses the coverage ratings and announced Tuesday it had scored a .88 for Sunday's broadcast of the NASCAR Truck Series race at Rockingham Speedway.

Low television ratings have been one of the biggest issues facing IndyCar.

The television package is split between two networks, with NBC Sports carrying 10 races on cable this season and six going to ABC, which broadcasts the Indianapolis 500. The long-term future of the series is with NBC Sports, which has just started the fourth year of a 10-year contract IndyCar signed with Versus before the 2009 season.

IndyCar is hopeful a bevy of changes this year and compelling competition and story lines will help widen the fan base.

But the season-opening race at St. Petersburg drew only a .9 on ABC, leading many in the industry to complain about the quality of the broadcast. NBC Sports' rating from the race at Barber was even more concerning to its participants, who praised the broadcast but questioned the network's promotion.

NBC Sports has been advertising IndyCar during the NHL playoffs on both the cable channel and broadcast channel NBC. It also celebrated its rebranding from Versus to NBC Sports with an IndyCar commercial during the Super Bowl.

Next up for NBC Sports and IndyCar is the April 29 race in Sao Paulo, Brazil. The network does not have another head-to-head conflict with NASCAR's Sprint Cup Series this season.