[QUOTE=Bryan Ekers]
I just wonder how much gas savings could be realized by automated highways - computers controlling thousands of cars cruising along at a steady 70mph a few feet apart. I expect that’ll beat rail travel and with the first baby boomers getting into their high-crash seventies, computerized cars may be inevitable anyway.
[/QUOTE]
Despite the statements disputing this savings, it is true. Drafting is a well established technique in racing both auto and cycles. In cycling, for example, a cyclist in the middle of a drafting pack travelling at 20 mph expends 30 - 40% less energy than the leader of the pack. Moreso, the leader of the pack is still better off than a solo cyclist subject to his own drag. Basic aerodynamics. By being tightly bunched (only possible for autos driven by drivers with the skills of pro racers or by computer controls) multiple vehicles behave as one long narrow object with greatly reduced drag. This effect is amplified at greater speeds and would be quite large for a train of say 50 cars travelling bunched behind each other at 60 - 70 mph compared to the same cars traveling independently at the same speeds.
As to Toadspiitle’s question about the relative energy saving using electricty vs gas … amply addressed in Who’s stopping the electric/solar car thread such as in this post in which the main cynic of an efficiency savings came to conclude that even using all coal fired power plants with no sequestation would result in more miles per carbon produced with electricity than with ICE. In this hypothetical, in which the weight of batteries was taken off of the car, and efficiency was added by drafting, the comparison becomes even more skewed. The issue would really be one of the expense (dollars and carbon expended) in building the infrastructure.