It is UK bias but as Wilf says we have global membership. 90% of stuff will be relevant, only thing that gets tricky is variance in trim level and what the trims are called (e.g. In the UK we have SE, Sline and Sline Plus rather than Prestige etc).
The only major equipment difference I know of (and this is the same for most cars) is in UK/Europe we get DAB digital radio, and in the US you get Sirius satellite radio.
The Q5 section of Audizine is very active and is very US bias FYI.