The Falcon is not too big for drifting. While I haven't seen this particular AU, I've seen FPV's DRFT6, which is a kind of boosted Typhoon prepared by FPV and a GTO, based on the previous model Commodore. Both these car worked beautifully despite the fact the both BA and VZ models on which they're based are considerably heavier than AU. See for yourself.
Also, check out
Ford Typhoon Drifting Car