Question

why bus does not have a streamlined shape while a car have ?

Answer 1

Well, having an aerodynamic trucks will be a better option, but there are certain issues due to which the front part of the trucks look like boxes.

An aerodynamic truck will have its frontal part in a curved shape. Now, a curved front will leave lesser cabin space for the driver and the cabin crew. However, there are design which have curved front but have good enough cabin space. Like the images below.


Bullettruck

I have seen most of the people here are answering that as trucks travel at lower speeds aerodynamics is not a big concern. Really? No, aerodynamics does play an important role which will affect the fuel economy and increases the drag forces on the vehicle, that is why you can see the above new generation trucks by Nikola Motor Company and AirFlow Trucks are having proper aerodynamic shapes.

To buttress my claims, a company called AirFlow trucks has done testing with its aerodynamic Bullettruck which travelled from Connecticut to California hauling 65000 pounds of load. The result of this test was rather surprising because this aerodynamic truck achieved fuel economy of 13.6 MPG and that's 50% more than what the non aerodynamic trucks can achieve.

So, the catch is that, aerodynamics has to be considering while designing a truck which will not only help reduce fuel consumption and cut fuel costs but also remove 'smoke' which is always related to trucking industry.

I think the time has come to move towards electric trucks and hybrid trucks which are either gas turbine+battery powered or diesel+battery powered. Companies like Tesla, Wrightspeed, Nikola Motor Company, Diamler+ Mercedes Benz, AirFlow trucks, Volvo are betting big on it.