I don't ever seem to be able to get above 2.6 or so efficiency. I'm mainly doing short drives of around 3 miles each way with heating on (air, steering wheel, and seat!). I get that the cold weather affects efficiency but are shorter journeys worse too? I find it creeps up on the return trip (perhaps because the car has warmed up slightly) but this morning i had 1.1 to 1.5 on the first leg! There are some hills but only around 20-30mph and I'm on auto regen level 3.