I have TACC set to 8% over posted limits. That's usually about 6 to 7 over. Having owned 3 Volt's since March 2012 I have learned SPEED KILL's an EV's range and truth be told, the speed demons seldom really get to their destination much faster since they usually consume more energy and need to spend more time replacing it at the next charging stop.What were your average speeds? We did a road trip and see closer to 300-310 Wh/mi when going 80-85 mph for long stretches (LR w/ Inductions).
The other thing, we are 68 years old and need to stop for BIO breaks well before the car needs a charge so whenever one of us need to stop (regardless of SoC) we stop at a SC'er and in that 10 or 15 minutes we add another 75 to 100 miles and NEVER have to worry about our wh/mi etc. I do think with EV's SLOWER can be FASTER.