A few times over the past few weeks when I put the car into park I got a message in the instrument panel stating that the parking brake didn't engage. Putting it back in gear and then back into park seemed to clear it. I brought the car into the service center for that and a few other issues and just got it back this afternoon. They replaced the left parking brake caliper assembly. I have a 120-130 mile drive that I take 2-3 times a week. I average about 280 Wh/mi over this trip and the best I have done is 276 Wh/mi. Surprisingly, tonight when I took the trip I averaged 262 Wh/mi. I realize that a lot of things can affect efficiency, but this is a good 5% better than my previous best which seems somewhat significant. The only thing I can imagine is that possibly the bad parking brake was remaining partially engaged when it was supposed to be off. It'll be interesting to see what happens the next few times I make this trip to see if this was just a fluke.