Penske, and all the rest...
The basic inaccuracy of the USF1 press release was the subject of much debate at Vulture Central. The last US F1 team to win a GP, as Mr Larrington points out, was the Penske team in Austria in 1976. The last US F1 team were Beatrice/Haas-Lola in the mid 1980s, although they never won a GP.
What I think USF1 are trying to do by discounting these efforts is to tap into the inherent patriotism of the US public. They have deliberately gone back not to Penske, (US team, British Engine, John Watson as driver, who was from Northern Ireland,) but to All American Racing, (US team, US-commissioned but British-built engine, American driver,) whose sole 1967 GP victory they use as their historical reference point. They refer to this victory as a win in a Grand Prix 'tournament'. This is a misleading term that might suggest to the uninformed that the team had, in fact, won the entire championship that year, rather than just one race. The fact that most Americans know little about F1 means they can use this to suggest that USF1 is the latest instalment in a long and distinguished history for American F1 teams, when in fact their record is less than inspiring.
The reason for this is not obvious, but the enthusiasm that patriotism generates can only be helpful in gaining sponsorship and support. USF1 have already suggested that they will be using new media and methods to gain the finance they will need to run the team, and I suspect that this attempt to paint USF1 as the latest instalment in a long history may be part of this. It would not surprise me, for example, if as well as the YouTube money, they also attempted to personalise the F1 experience by taking smaller, personal sponsorships for the cars and team in much the same way that Jan Lammers with his Racing For Holland Le Mans team. This would fit well with the YouTube sponsorship, too. The YouTube slogan is 'Broadcast Yourself', after all.
What baffles me is why the team chose to go with US teams rather than US drivers, as America does actually have history there, with Phil Hill and Mario Andretti both being world champion drivers.
Maybe that will become part of the media approach once they announce their driver line-up. Expect that to go ballistic, if Danica Patrick indeed joins them and becomes only the third ever female F1 driver.