A new design, new vehicle lengths, an all-new cockpit and a host of new interior and exterior features highlight the uniqueness of the ComfortClass 400 range. Launched in 2003, the ComfortClass 400 range comprises the S 415 GT, S 415 GT-HD, S 416 GT-HD and S 417 GT-HD models and opens up a new dimension in the combination of economy and comfort. In spring 2005 the product range was extended with the S 415 GT-HD and S 416 GT-HD right-hand-drive versions.

During the development phase of the ComfortClass 400, Setra took into account the lifting of legal regulations that limited the length of buses and coaches to a maxi­mum of 12 metres. The S 415 GT and S 415 GT-HD measure 12,200 mm, the S 416 GT-HD 13,020 mm and the S 417 GT-HD is 14,050 mm. This length concept, which is new to touring and private-hire coaches, yields noticeably more interior space than in comparable vehicles, while improving economy and comfort in a most impressive manner. The bodyshell construction featuring reinforcements stretching across the roof and down the sides - in which a series of transverse tubes are connected by means of side members - has been a decisive element in exten­ding the front end of the vehicles and making them up to 2550 mm wide. This system ensures a high level of torsional stiffness for the vehicle. As on the TopClass 400 coaches, the body framework is protected by cathodic immersion dip coating. At the front end, the vehicles are 60 mm longer than the previous models. The driver’s area is now 140 mm longer. The front entrance is also 70 mm wider thanks to the longer nose section. The new length concept makes boarding and alighting at the front door much easier for passengers. The engineers managed to gain another 70 mm to provide more generous seat spacing at the right, in front of the rear door. Despite the vehicle's increased length, the overhang angle has been increased to 7.65° - a particular advantage on narrow mountain passes or when entering bus-stop bays.

Another important feature of the ComfortClass 400 is the redesigned cockpit with its distinctive styling. All the controls have been arranged according to ergonomic principles. Now the touring coach-style driver's area features a joystick gearshift, integrated navigation monitors, an additional bottle holder as well as further stowage options for briefcases, maps and such like. The adjustable steering column, adopted from the TopClass 400, is equipped with a pneumatic locking mechanism. Furthermore, a cash desk can easily be installed in the cockpit if the ComfortClass 400 is to be used on rural regular-service routes.

The S 415 GT-HD, S 416 GT-HD and S 417 GT-HD models in the ComfortClass 400 range are equipped with the vertically installed OM 457 LA in-line six-cylinder 4‑stroke diesel engine with turbocharger, charge-air intercooler and direct inject­tion. The Euro 4 engine is available for the S 415 GT-HD with a power output of 315 kW/428 hp and a maximum torque of 2100 Nm. The S 416 GT-HD and the S 417 GT-HD are supplied with the 315-kW/428-hp engine as standard, offering maximum torque of 2100 Nm.

The S 415 GT-HD, the S 416 GT-HD and the S 417 GT-HD are equipped with the Mercedes-Benz MB GO 210 six-speed manual transmission with joystick control. The automated ZF-AS Tronic 12-speed manual transmission is available on request for the GT-HD models. The S 415 GT is fitted with the vertically installed OM 457 hLA in-line six-cylinder engine developing 220 kW and the GO 190 trans­mission. A version with a power output of 260 or 310 kW and the GO 190 trans­mission is available on request.

All vehicles are equipped with disc brakes, Voith Retarder VR 115 (ZF intarder in conjunction with the ZF-AS Tronic), Electronic Braking System (EBS), anti-lock braking system (ABS), acceleration skid control (ASR), Brake Assist (BA), and Electronic Stability Program (ESP). ESP has been standard on all TopClass 400 and ComfortClass 400 models since October 1, 2003.

The Setra ComfortClass 400 models offer ample space for the crew and passengers when loading and unloading luggage. The Setra S 415 GT-HD and the Setra S 416 GT-HD have two enlarged, hinged luggage compartment flaps on the left-hand side of the vehicle. An additional partition in the luggage compartment has been removed on the ComfortClass 400 models, which together with the reduction in the number of flaps guarantees more convenient access.

The entire electronics system is a combination of conventional switching systems and flexibly programmed FPS controls, the modules of which are networked via a CAN databus. FPS consists of several "intelligent" modules located decentrally in the vehicle - wherever something needs to be operated or controlled. The advan­tage of this networked electronics system is that fewer cables and relays are needed. Reduced complexity results in more reliable coach operation.