A couple vehicles I've driven lately, based on onboard fuel monitors:
05 Subaru Outback, city driving in -15 to -20 temps - 13.8L/100km.
05 Hummer H2, city driving in -15 to -20 temps - 25.5L/100km.
05 Hummer h2, hwy driving 110kph, -20, 18.5L/100km.