Looks like your source is correct. I searched tonight on my Comcast schedule and found it listed: 12 noon EDT on April 15. Listing says World Challenge touring cars and GT at Sebring, or something to that effect. Both races in one show?

The SpeedTV web site sort of confirms this. The noon time slot on that day says "NA" for the title and "Sebring" for the episode.

Recording is scheduled!