Many here suggest the battery should be occasionally cycled between 100% charge and near 0% charge to keep the charge measurement calibrated. So I did that a couple of times. The first time the battery took a very long time to finish after it had reached 100%. It indicated around 8 kW charging rate and I switched to miles which read 276. It rose to 277 by the time the rate declined to 6 kW. The miles did not increase for another 20 or 30 minutes until it stopped charging with the rate down to 1 kW. I ran the battery down to around 3% before charging again to 100%. This time it reached 276 miles by the time it stopped charging and took a while, but not 30 minutes after reaching 100%. There were two charges to 90% since then. I have been thinking the trip numbers were a little off, showing too small usage of kW for the percentage of the battery being used. This is a P100D, so the kW/mile should be pretty close to 1.0. I took down numbers from the trip counters. From 91% charge to 3% charge reported as 73 kW used. That's 73kWh / (91%-3%) = 83 kWh on a fully charged battery. Repeating the measurement on the trip home, a shorter distance, I get 24.3 kWh / (90%-62%) = 86.8 kWh on a full charge. This has nothing to do with mileage. This is just measuring how many kWh the battery will hold. If this is already 15% off the original capacity, I can see why my range seems to suffer. The car is not even a year old with 18,000 miles. I typically charge to 90% but sometimes charge to 95%. Virtually every time I charge the car is driven at least 30 miles afterword before it is parked.