Could be, could be, yes, yes, yes.
The "1/2 at 60" really sucks your battery. You are using an immense amount of power just to push you and the bike through the air. I commute on surface streets, mostly -- average speed about 35-40, with a one-way trip of about 12 miles. I arrive at work with my battery showing about 66% remaining. I could ride in via the highway, but unless I knew for sure I could charge at work (usually, I can't), I avoid the highways.