One critique is that the shorter wheelbase in the COE semi-trucks gives a rougher ride than those with conventional cabs, as the driver's seat is above the front axle. In the 1970s, COEs used to be noisier, because the engine is directly below. This was an important consideration back then: Interior noise in the cab was between 80 and 90 db(A), creating an unhealthy work environment. , US long distance trucks provide an interior noise level of 60–70 db(A) at highway speed, while European long distance trucks, all built as a COE, provide a level of 60–65 db(A). As highway speeds are a slightly higher in the US, this performance can be viewed as equivalent.