When introduced, British Rail described the Class 158s as bringing "new standards of comfort and quality to rail travel on Regional Railways' key long-distance cross-country routes".

As built, interiors were described as fully carpeted, with "panoramic" windows and a variety of seats arranged both airline-style and in bays of four around tables.
Unlike previous members of the Sprinter family, such as the Class 156 SuperSprinter, the Class 158s featured air conditioning, an on-board payphone, power-operated interior doors, a toilet in each carriage, and provision for a refreshment trolley service.
Despite an increased top speed of 90 mph (145 km/h), the units also promised a smoother, quieter ride than its predecessors.

The Class 158s were expected to achieve 13,500 miles (21,700 km) of operation between major services and a range of up to 1,600 miles (2,600 km) from each refuelling.
When introduced, British Rail described the Class 158s as bringing "new standards of comfort and quality to rail travel on Regional Railways' key long-distance cross-country routes".
As built, interiors were described as fully carpeted, with "panoramic" windows and a variety of seats arranged both airline-style and in bays of four around tables. Unlike previous members of the Sprinter family, such as the Class 156 SuperSprinter, the Class 158s featured air conditioning, an on-board payphone, power-operated interior doors, a toilet in each carriage, and provision for a refreshment trolley service. Despite an increased top speed of 90 mph (145 km/h), the units also promised a smoother, quieter ride than its predecessors.
The Class 158s were expected to achieve 13,500 miles (21,700 km) of operation between major services and a range of up to 1,600 miles (2,600 km) from each refuelling.
British Rail Class 158