Lot of aerodynamics went into that Cab! I remember a scale model of that was offered by way of the parts department.
If you zoom in on the picture it does have
those two left/right curved wind guide deflectors at the (very) sharp front windshield corners,
so that cab-over did see at least some wind tunnel time....
How did that weird pre-1986 Fed rule about maximum vehicle weight on an Interstate Highway bridge read
- the one that encouraged the extremely short cab-over tractor?
https://nodum.org/why-semi-trucks-in-us-and-europe-are-so-different/sample quote
Maximum length of a truck with a semi-trailer in Europe is 18.75 meters. Some countries have some exceptions, but generally that is the rule. In order to use the maximum of this length for the cargo the tractor unit has to be as short as possible. The best way to achieve that is to mount the cabin over the engine.
Similar requirements in US have been revoked back in 1986 and trucks now can be much longer. Actually, back in the day cab-over trucks were quite popular in US, but without strict limitations roomier and more convenient to live with conventional design trucks prevailed. The number of cab-over trucks in US is constantly declining.
Another reason is speed. In Europe Semi-trucks are limited to 90 km/h, but in some places in US trucks reach 129 and even 137 km/h. That is where better aerodynamics and longer wheel base help a lot.
Finally, roads in US and Europe are very different as well. Cities in US have wide streets and interstate highways are very straight and wide. In Europe trucks have to deal with narrow streets, winding country roads and cramped parking spaces. Lack of space limitations allowed Australia to use conventional cab trucks too. That is also why Australian highways feature well-known road trains – extremely long distances and straight roads allow semi-trucks to pull up to four trailers.
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