In the somewhat warm weather, I find it very easy to beat the EPA energy estimate. Driving to work and back and a little bit around the city, I went 49.5 km today. Total energy was 8.8 kWh and average energy was 177 Wh/km. This was a round trip so no net elevation change. This is based on the "since last charge" display. Over the last few weeks I've gone 1755 km with a total energy use of 337.3 kWh and an average 192 Wh/km. This is probably about 50% highway driving. Driving my Prius, I never came close to matching the EPA estimate. I think the rated energy is based on the EPA estimate of 193 Wh/km. +1 for Tesla.