Not that I disagree with you, but where did you read that it was directly modelled on the Autobahn?
I found this in wiki.
"Eisenhower gained an appreciation of the Reichsautobahn system, the first "national" implementation of modern Germany's Autobahn network as a necessary component of a national defense system while he was serving as Supreme Commander of the Allied forces in Europe during World War II.[9] He recognized that the proposed system would also provide key ground transport routes for military supplies and troop deployments in case of an emergency or foreign invasion."
Nothing in there says that anything to do with the Federal Insterstate system was modelled on the Autobahn, simply that it was recognised as a good thing by Eisenhower. This would indicate that the Interstate system, on which everyone drives in the right, has absolutely nothing to do with the Autobahn, on which everyone drives on the left.
