The American semi-trucks and European semi-trucks are very different.

The main difference is the overall design of the tractor unit. In Europe there are usually cab-over trucks, this type means the cabin is above the engine. This design allows the flat front surface and the entire truck with its trailer has a cuboid shape.

Meanwhile trucks used in the US, Australia and other places in the world use “conventional cab” design. This type means the cabin is behind the engine. Drivers will sit further away from the actual truck front and look over the long engine cover when driving.

So why different designs prevailed in different places in the world ?

One difference is that owners-operators are very common in US but not so much in Europe. These people have their own trucks and almost live there for months. Semi-trucks with conventional cabs will have longer wheel base, which can make drivers a little bit more comfortable. What’s more, they tend to have much room inside. Owners will reform their trucks to include huge living parts,which is not common in Europe. Without the engine under the cabin, in fact the cabin will be a little lower, which mekes drivers be easier to get in and out of the truck. 

Another advantage of a conventional cab design is economical. Of course both of them usually pull heavier loads, but if there are two trucks, one is a cab-over design and the other is a conventional cab design, when they have the same capacity and the same cargo, the conventional cab truck would most likely use less fuel theoretically. 

Besides, engine in conventional cab truck is much easier to reach which is better to maintain and fix. 

However, cab-over trucks do have their own advantages.

Square shape design makes it easier to let the truck close to other vehicles or objects. European semi-trucks are lighter and have shorter wheel bases, which makes them significantly easier to operate. Essentially, they are more compact and easier to work with in traffic and urban environments.

But what are other reasons why different truck designs prevailed in US and Europe?

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Similar requirements in US have been revoked back in 1986 and trucks now can be much longer.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.