Hi Trill, we also bought ours new in 2007. As mentioned, we went for the slimmest boosters we could find and had all three seats fitted by Qld Ambo service to ensure a proper/accurate fit. The fellow made it clear he wasn't enthused by 3 seats in a Captiva, but he mucked around until he got a good and legal fit.

While I love my Captiva, I'll be more conscious of that middle seat when we go to buy another car.