Just 39 million viewers watched an average race in the 2003 season, compared with the 162 million claimed by FOM, Initiative Futures revealed in its ViewerTrack report.
Initiative said that it reports figures after each race, as opposed to FOM, which only reports viewing figures at the end of a season.
However, the discrepancy is likely to have been created by the different sample size used by Initiative - FOM collates viewing figures from 173 viewing territories, while the Initiative data includes viewing figures from just the top 38 viewing territories.
Initiative found that F1 viewing figures were up year on year for the first race of the 2004 season in Australia. It reported more than 37 million viewers worldwide watched the Australian Grand Prix, up by four million compared with last year.
The first race of the season was most popular in Australia with an 11.4 per cent rating and 2.6 million viewers. In Brazil, it was watched by 4.6 million viewers, a rating of 9 per cent.
The UK rating was 4 per cent of the television viewing population, although this figure is a reflection of the late-night scheduling of the race.