I find that an interesting correlating report - thanks . I'm tempted to go back the same way tomorrow and see if it happens again although I don't believe it will in any way convince the "mysterious headwind" believers . I've noticed several anomalies in the extreme heat. My shift lever went wonky which I put in another thread and several times I noticed that after 10+ minutes of driving with charge going to the battery all the while - the battery stayed at 1 bar. I stopped and tried to charge it by using brake and pedal but it still stayed at one charge until the temp went lower (it was 115 outside at the time). There are definite anomalies in the Prius at extremes of heat and I don't find it surprising that altitude (below sea level) could also contribute its own set of anomalies.