Indeed, it is very difficult, and I've now proven that to myself! I didn't mention this in my original post, but another factor that made conditions more ideal than the average commute was, being Saturday morning in Edmonton, it wasn't busy at all. I had roads largely to myself, and when stopped at traffic lights, I had 1 or 2 cars in front of me at most. I couldn't dream of averaging even 19 mph on a regular weekday morning.