- Economical and clean engines comply with EU emissions standards Euro 4, Euro 5 and EEV
- Citaro LE: Low Entry, the alternative for urban and rural traffic
The Mercedes-Benz Citaro is already one of the best-selling regular-service buses bearing the Mercedes star. With nearly 15,000 models sold since series production began in 1998, it can be seen on the streets of almost all of Europe’s major cities. The Citaro was first introduced at the UITP Congress in Stuttgart in 1997, and since then it has enjoyed a string of successes as a bus for regular-service urban and rural operations. Now, the second generation is on the way: the Citaro has been revamped technically and visually in a number of respects. At the same time, three low-entry variants and the new Mercedes-Benz Citaro K are rounding out the Citaro range of regular-service urban and rural buses. The “shortened” Citaro K urban bus was unveiled publicly at the IAA Commercial Vehicle Show 2006 and is making its debut in Spain at the FIAA 2006.
Mercedes-Benz Citaro: unique range of low-floor regular-service buses
The new Citaro K, a compact variant measuring 10.5 metres in length, is now extending the already broad range of the best-selling Citaro regular-service bus. That means the range of the low-floor regular-service Citaro now consists of 11 variants with a large number of different lengths that fully cover all the transportation needs of local public transport operators in urban and rural transport. In addition to the brand-new Mercedes-Benz Citaro K, the urban buses include the 12-metre Citaro, the 15-metre Citaro L and the Citaro G articulated bus with a length of 18 metres. For rural service, Mercedes-Benz also offers the Citaro Ü (12 m), Citaro MÜ (13 m), Citaro LÜ (15 m) and the Citaro GÜ articulated pusher bus (18 m). Further new additions to the range include the Citaro “Low Entry” regular-service bus — first unveiled in autumn 2005 — which is available as an urban bus (Citaro LE, measuring 12 m in length) or as a rural bus (Citaro LE Ü and Citaro LE MÜ, measuring 12 m and 13 m in length respectively). All in all, these vehicles make up a uniquely varied and comprehensive range of low-floor regular-service buses for urban and rural transport.
The 19.54-metre Capa-City large articulated bus is likewise derived from the Citaro range. In addition to diesel-drive vehicles, the range also includes regular-service buses with natural gas drive systems. The well-known limited edition bus with the fuel-cell drive was also developed from the Citaro model range.
Mercedes-Benz Citaro K: compact and highly manoeuvrable
The new compact variant of the Citaro was developed from the versatile modular system of the Citaro range in the tried and tested manner: it is based on the 12-metre Citaro, whose wheelbase was shortened by exactly 1447 mm, from 5845 mm to 4398 mm. The front and rear overhang are identical to those in the original model. The result is a compact, 10.5-metre, two-axle low-floor bus with two entry doors, a vehicle ideal for regular service on urban routes with low passenger levels. Because the kerb weight is about 900 kg less than that of the 12-metre Citaro while the permissible gross vehicle weight remains unchanged at 18 tonnes, the Citaro K offers a maximum passenger transport capacity of between 85 and 91 passengers, depending on the seating (106 passengers in the 12-metre Citaro).
The reduced wheelbase also leads to exceptional manoeuvrability. The turning circle measures only 17.2 metres, almost four metres less than the already very manoeuvrable Citaro urban bus with a length of 12 metres. Also noteworthy is the small swept ring of only 4.6 metres width in the case of tangential entry into a
25-metre circle (12-metre Citaro: 5.7 m). That makes the Citaro K perfect for routes in very narrow and winding inner-city streets. Thanks to its comparatively high passenger capacity, it is also flexible enough to operate on all other passenger routes without any restrictions.
The new Citaro K is powered by the proven in-line Mercedes-Benz OM 906 hLA Euro 4 turbodiesel with six cylinders in a horizontal arrangement. This compact Euro 4 engine, which uses Blue-Tec diesel technology from DaimlerChrysler, has an output of 210 kW (286 hp). This engine, available in many other Citaro models as well, is already available in versions complying with the more stringent EU emissions standards Euro 5 and EEV (Enhanced Environmentally-friendly Vehicle). The drive power is transmitted by an automatic converter transmission with four to six speeds, available from either ZF or Voith. Like the drive system, the running gear of the Citaro K, including the size 275/70 R 22.5 tyres, comes directly from its large “urban bus brothers” — an essential benefit for maintenance, service and spare-parts stocking for vehicle fleets and in workshops.
The Citaro K benefits from the exemplary attributes of the Citaro: it is designed with a low floor throughout, from the front to just in front of the rear axle. Whether it be doors, destination displays, the cockpit or the furnishing of the passenger area with seats and grab rails: all these proven components come directly from the Citaro. This is also true of the many changes with which the second generation of the Citaro is now being launched.
A regular-service bus with a “face”
The “face” of the second-generation Citaro is itself striking and was shown to the automotive world for the first time in conjunction with the premiere of the new low-entry variants Citaro LE (urban), Citaro LE Ü and Citaro LE MÜ (rural) in October 2005. New features include a curved recess between the headlamps, which looks like a radiator grille and creates a visual link with the latest Mercedes-Benz touring coaches and rural buses. Within this recess, the Mercedes star is now displayed on its own special base.
The indicator housings, now rotated upward, contribute to the Citaro’s friendly appearance. They now have clear-glass covers, along the lines of the main headlamps. An all-black moulding extends the windscreen downward, making the wiper arm attachments seem as if they are set further back. The front-end cover is flush-mounted, and the bumper features smoother lines for a “softer” shape. At the front end, bolting points are no longer visible in the new Citaro regular-service buses. In addition to the front-end flap, the corner panels, including the headlamp housings, can be folded forward as well — so the whole front end is perfectly accessible for maintenance work. The different windscreens for the urban and rural buses and the destination displays have remained unchanged.
Rear shaped with powerful contours in three dimensions
The rear of the Citaro is now fleshed out more in three dimensions and has elegant lines. The rear window, given a dynamic V-shape, extends far upward and reaches into the roof. The engine cover ends at the top in a ventilation opening, sealed by a black mesh plate. The whole design vocabulary of the Citaro evokes the new generation of touring coaches and rural buses from Mercedes-Benz. This is signalled as well by the prominent tail lights with a common glass cover. They reach around the sides a great distance, are sloped, and are made up from the same modules as on the new Travego. The bumper also has a new design.
Taken together, all the modifications remove the severe and angular shape that the regular-service bus usually had in the past; they give it a softer and more harmonious appearance. Attentive observers notice the new frameless, hinged windows and the consistent grey tint to the windows instead of the previous green — except for the windscreen, the driver window and the front entry door.
Refined interior and driver area
The design vocabulary of the interior has been refined too. The angled, side ceiling panels pass almost seamlessly into the ceiling, which is flat and smooth for easy cleaning and trimmed in aluminium. The strip lighting has been adapted to the form of the new ceiling in appearance. In the passenger area, new urban bus seating is used. The new passenger seat “City-Star Eco” is available in several versions. Compared with the predecessor, it features comfortably enlarged dimensions (+ 24 mm) but the same seat spacing. In addition, each seat weighs 0.7 kg less. Depending on the seating variant used, this means a weight saving of about 25 kg to 30 kg per bus.
Also new in the Citaro is the Opticool windscreen. Already tried and tested in the Mercedes-Benz Travego touring coaches, it acts as an excellent thermal insulator, absorbs infrared radiation and allows about 10 % less heat and energy through. That significantly lowers the temperature in the interior and thereby increases the comfort of the driver. The interior design of the front end has been enhanced visually, too. The Mercedes-Benz brand lettering welcomes passengers right at the entrance; a closed cover in the semicircle of the instrument panel panelling conceals the fire extinguisher, previously mounted openly.
The driver area still has the proven VDV instrument panel. On the left-hand side are a number of large new shelves that can be augmented by an optional electrically cooled bottle rack. The parking brake lever and easily reachable console switches for additional functions are also on the left.
Economical and clean Euro 4 and Euro 5 engines,
certification according to EEV available
All of the standard engines for the second-generation Citaro models are Euro 4 powerplants using Blue-Tec diesel technology. The wide range of engines for the Citaro satisfies all power output requirements. The very compact and lightweight OM 906 hLA six-cylinder in-line engine has a displacement of 6.4 litres, an output of 210 kW (286 hp) and a peak torque of 1120 Nm at 1200–1600 rpm. The OM 457 hLA six-cylinder in-line turbodiesel engine has a displacement of 12 litres, a choice of outputs — 220 kW (299 hp) or 260 kW (354 hp) — and a maximum torque of 1250 Nm at 1100 rpm or 1600 Nm at 1100 rpm respectively. In the second-generation Mercedes-Benz Citaro, this engine is available in a Euro 4 version equipped with Blue-Tec diesel technology. All the engines provide impressive pulling power at low engine speeds, which is especially important for pulling away quickly in urban traffic, even when the bus is full.
The Citaro can also be delivered with diesel engines that already satisfy the Euro 5 emissions standard in effect from 2008/2009 onward. Initially, the OM 906 hLA will be used with the same power output and torque specifications, followed in the spring of 2007 by the OM 457 hLA. At the same time, horizontally installed versions of these two engines will also be coming on stream; these even comply with the more stringent EEV (Enhanced Environmentally-friendly Vehicle) emissions standards — further proof of the great potential and the future viability of the Blue-Tec diesel technology. In this engine, a sintered metal particulate filter is also used.
Independent front suspension improves comfort and handling
There has been considerable improvement to the hidden features of the Citaro as well, and not just to those in clear view. One new feature in the Citaro is a front axle with independent suspension. The design is based on lower wishbones and has standard-fit stabilisers. Benefits of the independent suspension system include impressive straight-line stability, less road impact on the steering, a substantial weight reduction, lower unsprung masses and a general improvement in handling and ride comfort, since the wheels do not affect each other if the road conditions are worse on one side of the vehicle than they are on the other.
Although the entrance height has remained the same, the ground clearance of the Citaro has increased to 165 mm beneath the front axle, thus reducing the risk of bottoming. The steering gear has been moved back and is now outside of the area at risk in the event of an accident. The front axle has a very large steering angle (inside 53 degrees, outside 46 degrees), without any restriction of the aisle width of 910 mm between the wheel arches. As a result, the turning circle of the 12-metre Citaro variant has been reduced by half a metre from 21.5 m to just 21.0 m. The larger variants also have smaller turning circles than before: 23.7 m (Citaro MÜ), 24.3 m (Citaro L/LÜ) and 22.9 m (Citaro G/GÜ).
The driver and passengers also benefit from heightened ride comfort: the maximum spring travel has been increased by more than a third from 70 mm to 94 mm; the air spring volume per bellows has been boosted by over 10 % to 10.5 dm³ and the natural frequency has been reduced substantially. The result is handling that proves to be unusually sure, smooth and comfortable for a low-floor bus.
Mercedes-Benz Citaro G and GÜ with roll/pitch control as an optional extra
In the articulated bus variants of the Citaro, handling and ride comfort have recently been improved even further by an optional roll/pitch control. In this system, the characteristics of the dampers at the front and middle axles are controlled electronically as a function of the driving situation and load. During braking or in dynamic cornering, this means increased safety thanks to firm damping. In other driving situations, the softer damping leads to higher comfort. Furthermore, roll, pitch and lifting movements of the body are reduced and attenuated more quickly, which becomes noticeable especially in an articulated bus. Reduced variation in the wheel load also protects the roads. Together with the independent suspension at the front axle, this leads to ride comfort that sets new standards for an articulated bus.
Mercedes-Benz Citaro LE, “Low Entry” with low-floor design all the way to the rear axle
The supplementary new model series Citaro LE (Low Entry), which was introduced in autumn 2005, anticipated the visual and technical changes to the Citaro. The term “low entry” gives it away: from the front end up to and including the middle entrance, buses of this category are full-fledged low-floor buses which take on the character of raised-floor vehicles after the second entrance door. On the one hand, this mixed principle leads to high entry and ride comfort, even for passengers limited in their mobility. On the other hand, it makes the installation of the engine and related assemblies simple, economical and service-friendly.
The new Citaro LE therefore combines the advantages of low-floor and raised-floor buses. Both regular-service buses, the Citaro LE and the Citaro, are nearly identical up to the area of the middle door. The drive train in the rear of the Citaro LE is likewise a proven and economical standard product. The engine, transmission and drive axle, including the substructure framework, come from the Integro rural bus.
Since the roof is raised from the middle of the vehicle onward, the Citaro LE has standing room even in the rear area. But it is only raised where necessary and useful: because the standard Citaro vehicle body was adopted in the front section, the new low-entry variant features a pleasant and harmonious sense of space at both the front and rear.
Newly designed, elegant exterior appearance for the Mercedes-Benz Citaro LE
Typical of the Citaro LE is the trim external appearance, brought about by the 310 mm increase in roof height from the middle of the vehicle onward. Lateral extensions create a smooth transition from the front section of the vehicle to the rear. The raised roof structure is covered with glass-fibre reinforced plastic and gently levels off toward the sides, another factor that makes the bus appear less tall than it is. At the rear, the raised roof flows with an elegant sweep into the newly designed back panel. The design vocabulary of the rear largely corresponds to that of the new second-generation Citaro; the front section of the buses is identical.
Smooth transition from front to rear section in the Citaro LE
In the passenger area, the Citaro LE again reveals its close kinship with the Citaro in its seating and layout. But the rural bus variant of the Citaro LE has redesigned seating created especially for this application. The Citaro LE has a characteristically smooth, curved transition from the low-floor front section to the raised rear section. Displayed with élan at the crossover of this perfectly implemented transition is the Mercedes brand lettering.
From the rear axle, two low 200-mm-high steps lead up to the high deck in the rear. The floor slopes up at a maximum of seven degrees here, and the standing room height is at least 1.90 metres, thanks to the raised roof. The higher floor and the 200-mm-high platforms (maximum) lead to a very homogeneous arrangement of seats in the rear part of the vehicle. There, all passengers sit facing in the direction of travel and the seats are staggered behind one another like in a theatre.
Citaro LE features comfortable and economical rear axle
from the touring coach
The driver area, revised in detail, and the new, comfortable and handling-optimised front axle with independent suspension in the Citaro LE correspond to those in the Citaro. Because of the raised-floor design, however, the rear axle is the HO6 hypoid axle, which has been a tried-and-tested performer for many years now in several vehicles, including the Mercedes-Benz Integro, Tourismo and Travego.
The big advantage of the hypoid axle over the portal axle in buses with a continuous low floor is the single-stage ratio of the centrally positioned differential with correspondingly low inner frictional resistances and the good fuel consumption values that result. At the same time, the noise level is reduced. The generous dimensions of the installation space at the rear axle of the Citaro LE also permit an exceptionally effective suspension offering coach-like comfort.
Maintenance-friendly, economical Euro 4 engines with Blue-Tec diesel technology is also a feature of the Mercedes-Benz Citaro LE
The drive train of the Citaro LE uses standard components from the low-floor Citaro and from the Integro rural bus. In contrast to the Citaro, the engines in the Citaro LE are always installed in the middle of the rear for very easy maintenance. The base engine is the Euro 4 version of the six-cylinder in-line OM 457 hLA with 12-
litre displacement. The horizontally installed engine is available in the output ratings 220 kW (299 hp) and 260 kW (354 hp).
As in the case of the Citaro, the automatic transmissions of the Mercedes-Benz Citaro LE come either from ZF or Voith, depending on the preference of the customer. For the rural-service bus variants, the six-speed manual transmission Mercedes-Benz GO 190 will be available in connection with the new automated gearshift EPS 3 beginning in early 2007.
Three Citaro LE variants for urban and rural transport
The Citaro LE range comprises two-axle urban and rural buses. The urban bus Citaro LE is available in a length of 12 metres with two or three doors. The two rural bus versions Citaro LE Ü (12 m long) and Citaro LE MÜ (13.1 m long) have two entry doors. The urban bus Mercedes-Benz Citaro LE can transport a maximum of 101 passengers; the Citaro LE Ü can carry 83 persons.
The Mercedes-Benz Citaro regular-service buses at the FIAA 2006 in Madrid
The broad model range of the Mercedes-Benz Citaro will initially be represented at the FIAA 2006 by the new Citaro K with the new Euro 5 turbodiesel OM 906 hLA. Its equipment package includes an infotainment system with two 19-inch flat-screen monitors, a mechanical folding ramp at the middle entry door, the “City-Star Eco” seating, a powerful air conditioning system with an output of 32 kW, a separately adjustable driver area air conditioning system and a Voith automatic transmission. A low-entry Mercedes-Benz Citaro LE Ü rural bus shows the advantages of the low-entry design. The drive train consists of the in-line six-cylinder OM 457 hLA with 220 kW (299 hp) and ZF automatic transmission. The passenger area is equipped with the new “Inter-Star Eco” rural bus seats.