Mercedes-Benz-Blog TRIVIA: Mercedes-Benz Bus History - PART VIII


Stuttgart, Germany, Oct 30, 2008

A hard act to follow for the O 404

* New face and luxury concept

* Draft-free heating concept for optimum comfort

* Very close to a passenger car

In early autumn 1991 the bus world suddenly seemed to spin faster. After 17 years the long career of the internationally best-selling Mercedes-Benz O 303 was approaching its end. A touring coach after the O 303? Hard to imagine. But in the new O 404 Mercedes-Benz unveiled a touring coach the like of which the world had never seen.

Technically and visually the new O 404 was a clean break with its predecessor, which in many respects still went back to the O 302. The O 404 boasted an all-new face, with tapered headlamps merging into the side turn signal repeaters. A radiator emblem linked up the two headlamps and spilled over slightly into the bumper, loosening the rigid forms of its predecessor. The large, steeply-raked windscreen blended harmoniously into the roof since the fresh air intake for the roof ventilation was moved further towards the rear. Borrowing a stylistic feature from its predecessor, the roof dipped down slightly to the front – although without the visible step of old.

The sides of the touring coach also had a totally new look to them. The first side window was drawn further downwards; the window guides were now virtually invisible. As on the outgoing model, the top of the side windows once again curved slightly into the roof. One of the special features of the new touring coach was its body paneling with deep-drawn parts, made necessary by the visual trick of the “facette.” This paneling lent structure to the side walls and took away their two-dimensionality. On the higher-specification variants, the large luggage compartment doors opened upwards in a parallelogram form. The entire body was designed for long-term durability: cataphoretic dip primer coating provided a reliable layer of anti-corrosion protection for the frame and paneling.

Streamlined range, concentration on touring use

The new model family was a lot more focused than its predecessor, with the emphasis limited to a much greater extent on use as a touring coach. The O 404 range consisted of three lengths – 9.2. 10.7 and 12.0 meters – and three height options: 3.3 meters (RH), 3.5 (RHD) and 3.75 meters (SHD). This allowed the O 404 to cover all the major areas of use for coaches, from short excursions to long-distance touring, including combination services, although it generally enjoyed a loftier positioning than the outgoing O 303. Further evidence of this arrived in the shape of an additional model which Mercedes-Benz unveiled to explore the potential for the brand in another dimension of travel. A double-decker variant of the O 404 was presented at the International Commercial Vehicle Show in 1992. Mercedes-Benz commissioned Heilbronn-based body manufacturing specialist Drögmöller to build the body for the coach, as the production lines at the Mannheim plant in the early 1990s were not equipped to handle vehicles of this size. However, public reaction was distinctly underwhelming and the double-decker remained a prototype.

It was all change as well underneath the impressively sculptured skin of the Mercedes-Benz O 404. The three equipment classes – Comfort, Luxury and Super-luxury – were designed with different uses in mind. The heating concept was certainly luxurious, not to mention unique. The engineers focused their efforts on the heat emitted by the floor and sidewalls of the coach and even introduced heated window sills to help create a constant and draft-free interior climate and a welcoming sense of warmth and comfort. The days of fan-blown heating in touring coaches were over.

Cockpit entirely redesigned

Drivers had a completely newly designed cockpit at their disposal. Gone was the familiar instrument cluster from the O 303 and its predecessor, now the instruments and auxiliary displays fanned out under individual glass covers. Numerous stowage compartments accommodated all sorts of odds and ends and the refrigerator was positioned at the bottom of the center console. A driver’s door was fitted as standard alongside other items offering extra refinement, such as an electrically adjustable rear-view mirror.

The chassis also bore some extravagance hallmarks. It had taken a long time for independent wheel suspension to make its debut in a Mercedes-Benz coach, but it was worth the wait. The construction was largely identical in principle to the multi-link independent suspension used in the brand’s passenger cars. And that meant a combination of unbeatable active safety and outstanding comfort.

The new model also had an incredibly large wheel angle of a maximum 56 degrees with a correspondingly small turning circle – the O 404 was astonishingly maneuverable. The anti-lock braking system and acceleration skid control were both fitted as standard, as was an engine brake with constantly open throttle valve and a retarder. With the exception of the Comfort trim variant, all the O 404 models came with disk brakes all round.

Engines to 503 hp

Mounted in the rear of the Mercedes-Benz O 404 was a new generation of powerplants. V6 and V8 engines covered an extremely broad output range from 151 kW (205 hp) to 370 kW (503 hp). The most powerful unit of the lot was reserved for the double-decker model, which was still at the prototype stage. All the engines originated from the company’s LEV (Low Emission Vehicle) family and already met the exhaust emissions stipulations due to come into force in 1993. The V6 power units represented the focal point of the engine range and delivered up to 250 kW (340 hp) – respectable engine power for a long-distance high decker in the early years of the O 404. Power transfer was the job of the brand’s own newly developed six-speed manual transmission.

The sophisticated technology at work in the Mercedes-Benz O 404 elevated it above the ranks of mere coaches into something more akin to a passenger car, a kind of super-sized MPV. This would actually turn out to be a handicap to the O 404 through its life, with series production struggling to get off the ground on account of the coach’s complex design (the O 303 continued to roll off the assembly lines until the middle of 1992). Added to which, the extraordinarily sophisticated and advanced engineering of the O 404 propelled it into different market segments from its predecessor – whose popularity it could consequently never match, even though Mercedes-Benz had used various measures to adapt the high-end touring coach to what the public wanted.

Drum brakes had been banished even before the O 404 went into series production, as they had been replaced by high-safety disk brakes on all models. Similarly, the seriously extensive engine range was also slimmed down, with 290-hp and 340-hp variants, and a V8 developing 382 horsepower, considered ample choice. The LEV engines designed to meet the Euro 1 exhaust emission standard may not have been particularly economical, but that all changed a few years later with the arrival of the Euro 2 power units. To the delight of coach specialists, large-capacity rear-mounted V8 engines with 14.6-liter displacement were back on the menu – the compact 12.8-liter V8 favored in the early days of the O 404 had fallen short of the mark.

And that wasn’t the end of the changes for the O 404 – far from it, in fact. A new addition to the range of variants – the Advantage – came with reduced trim levels and took the coach down a notch in the price stakes. With new and larger exterior mirrors, a ribbed front molding in place of the original stainless steel plate, and turn signal repeaters in white instead of orange, the O 404 hit its best form – both technically and stylistically – as it entered the mid-1990s. It remained in production until 1999, before being succeeded by a totally new breed of touring coach: the Mercedes-Benz Travego. Before it was pulled from the range, however, Mercedes-Benz had cleverly added a couple of siblings to the O 404. Built in Turkey, the reasonably-priced O 340 and O 350 high deckers - which later morphed into the Tourismo – turned out to be an almost accidental runaway success and heralded the dawn of a new era.

Copyright © 2008, Mercedes-Benz-Blog. All rights reserved.

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