im not sure whether things are that easy. quite often, maximum performance is indicated with respect to each aspect regardless of the others. for example, a 767 may maximally travel 10440 km - but not with full load of pax and/or cargo, while an A330 might be able to do so. or the other way around. however, you'd need more specific figures to compare relative fuel burn.
by the way, i just surfed around SAS's tec-ops page (www.sasflightops.com). they tried to explain why they have chosen A330/40 to replace their b767. one reason was that the 767 could not carry both maximum pax and cargo to very long haul destinations while the a330 could.
however i'd be interested in reliable estimates of those beauties relative fuel burn.