The Rivian S1 document filed at the SEC at the beginning of September was a first chance to see how well it was doing financially, but Tesla fan-boy publication CleanTechnica this week highlighted the ambition Rivian has for subscriptions, so we took another look at it – and it raises even more question marks over its forthcoming IPO. This is especially true given the hammering we gave General Motors for saying that it would double revenues in the next decade, partially based on the sale of subscription services, in our lead last week. On the one hand we would prefer to believe a pure EV play that it will attract extra revenues for software updates and services both sold and…