Your estimations are probably very far off. The Roadster was announced with a 200kwh battery, which is twice the capacity of the best Model S. Yet the Roadster

Your estimations are probably very far off. The Roadster was announced with a 200kwh battery, which is twice the capacity of the best Model S. Yet the Roadster is much smaller, and the 0-60/quarter mile times indicate that it is much lighter. So, we can conclude that Tesla is accounting for some real technology optimization in their batteries over the next 4 years, which I'm sure the Semi will see as well.