PlayStationBlog.it write "Sony announced that Gran Turismo 5 shipped 5.5 millions worldwide. Effective Sales? 2.9 millions!"
Wrong Types News - it's not official numbers. Thanks user: Brutallyhonest.
About Sony Official Numbers - Sell-in means Shipped in marketing language: Selling-In
the process of educating the salesforce and distributors to sell a new product as part of the preparation for its launch; the development of sales kits, briefings on the target market and competition, and outlining the organisation's plans to create consumer demand may be involved. See Commercialisation; New Product Development.