If you are a foot off the bumper of the car in front and it slams on the brakes then the speed differential at impact isn't very much. If you are two seconds or 150 feet off the bumper and not paying attention the car can come to a complete stop in front of you and you hit it going 65 MPH.
The best way to do a road train would be to put an 18 wheeler in front, incapable of stopping faster then the cars behind and punching a big hole in the air. The cars behind can help improve the poor aerodynamics of the blunt end of the back of a semi trailer. Everybody benefits.
If there was a way to physically couple the cars that would be even better. Motors could take turns running at BSFC pulling or pushing and maintaining climate control of the individual cars and then engine off coast for share. Even small pods of 5 cars would work really well. 30 seconds on, and then 2 minutes off, all five cars share the same frontal area and overall improved cd along with automatic pulse and glide that doesn't actually gain or lose speed.
Far fetched? I would never have imagined 10 years ago powerful connected computers would be in everyone's pocket and this technology grows exponentially.
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