In our 19 months of ownership, one thing that has come clear is that when the car is driven in rainy conditions, the energy consumption goes up quite a bit. I do not know if it is the added resistance of the rain on the road, the constant use of the windshield wipers, or a combination of both, but I have seen as much as a 30% drop in mileage, driving the same route, in the rain as compared to a non-rainy day. These were on trips of almost 100 miles over the same road.