Range on 23 Platinum

Took a 147 mile trip this morning and was very unimpressed with the range performance. I started out at 320 miles (100% charge) and at the end of the trip I was down to 55 miles left. Speed was 63 for about 30 miles of it and the rest of the trip was 74. No wind, pretty much flat and the temp was low 30s. Showed 1.5 miles per KWH. Does this sound normal?