Test Drive: Mercedes-Benz Citaro

The Mercedes-Benz Citaro is not the cheapest single-decker on the bus market, but it has an aura of quality which, in the right application, is well worth the outlay. The first Scottish operator to take the Euro 6 Citaro was McGill’s, and Tim Deakin drives one of them.

The Citaro has met with reasonable sales success since introduction to the UK in 2000, and sales of the revamped model at Euro 6 have been encouraging. As with most of the German builder’s vehicles, the market regards it as a premium product – but does it live up to the hype?

Greenock-based McGill’s Buses was an early customer for the Euro 6 model, and answers that with a clear ‘yes’. It took 14 for its flagship Clyde Flyer services in late 2014. After a handful of teething problems the Citaros have settled in well on what is demanding work, where they will each cover in the region of 150,000km per year.

While the Clyde Flyer group generates a strong demand from Glasgow to the coast, it also sees high peak demand from commuters working in Scotland’s largest city, competing with the parallel railway for both markets.

Although price is a key part of McGill’s weaponry, service quality is equally important. That’s where the Citaros come in, although a double-decker is allocated to one duty for capacity reasons.

“The Citaros have been a big hit with passengers. While it’s early days, we have seen patronage gains since their introduction,” says Marketing Manager Isabelle Murray. “We went for a high specification to make the service as attractive as possible, but even so, the buses are real head-turners. They have been very well received in the areas they serve.”


With McGill’s Euro 6 Citaros around ten months old, Managing Director Ralph Roberts kindly made one available for a routeone Test Drive.

Dimensions-wise the Citaro is little different to other single-deckers, be they lightweight or heavy-duty types. It’s 12.14m long and 3.10m high and seats 41, including three tip-ups; separate buggy and wheelchair areas are provided.

A number of subtle external styling changes have been made at Euro 6, most obvious of which are small ‘flares’ above each wheel.

Mercedes-Benz’s three-pointed star is prominent and the manufacturer’s identity is also clearly visible on the cab door. This is important for McGill’s, as the premium German brand resonates with aspirational commuters, says Isabelle.

Power is from the six-cylinder 7.7-litre OM 936 engine. With the exception of two more cylinders, its architecture is identical to the 5.1-litre OM 934 supplied by Daimler to other bus builders, which has proven popular at Euro 6.

The OM 936 develops 295bhp, putting the Citaro at the top of the power league for Euro 6 single-deckers. It is coupled to the six-speed ZF EcoLife gearbox, giving a driveline well suited to interurban operation.

The engine is in line, but to accommodate the full-length low-floor, it is mounted horizontally on the extreme rear nearside. While an unusual arrangement, it has its benefits, says Chief Engineer Grant Pirie; the top of the engine is easily accessible, for example.

The radiator is above the engine at head height, which is also beneficial. It prevents a build-up of road grime on the core, which could affect efficiency. Grant notes that the OM 936 runs around 10oC hotter than engines in earlier generations of Citaro.

Subtle restyling for Euro 6, but Citaro is still highly distinctive Subtle restyling for Euro 6, but Citaro is still highly distinctive


Passenger access

Access is via standard two-piece doors with a manual wheelchair ramp fitted. Wheelarch intrusion into the saloon is naturally greater than on a lightweight bus with smaller wheels, but the ‘throat’ is easily negotiated.

A single seat is ahead of each front wheelarch; immediately behind are the wheelchair and buggy areas, on the nearside and offside respectively. Priority seats come next.

17 fixed seats and the three tip-ups are reachable without encountering a step. The flat floor extends to well behind the rear axle, although seats from around the two-thirds point are platform-mounted.

The emergency exit is amidships on the offside, while a number of windows are also marked as such. Hammers are hidden behind breakable glass in the coving panels, which should go some way to dispel any temptation to remove them for other reasons.

The rear row of three seats is reached via a substantial step and sits next to the nearside-mounted ‘shower cubicle’. Although the extreme rear is well lit, it is slightly claustrophobic.

Curiously, Mercedes-Benz has not spread the bell pushes out throughout the bus. Most are towards the front, with few at the rear. Ralph explains that EvoBus is aware of this, and will shortly install additional stop request buttons.

McGill’s has opted for Mobitec destination equipment, which displays in white. It has also specified a repeater above the rear windscreen which shows both the service number and destination.

Access is good, with rapidly-acting kneeling facility Access is good, with rapidly-acting kneeling facility


Passenger comfort

With the Citaros on routes where many passengers have a car or train alternative, serious thought went into the specification.

At the front a bin is provided, while comprehensive internal and external CCTV is fitted. Seats are high-backed, with the headrests finished in synthetic leather. McGill’s logo is stitched into this part of the seats, undertaken during build in Germany.

All forward-facing seats accessible without encountering a step are of the cantilever type, simplifying cleaning of the bus, while wheelchair restraint bars also ‘swoop in’ at the bottom and are mounted close to the side wall. The floor is wood effect, adding to the quality feel. Wi-Fi is provided.

To complement the four opening windows a roof-mounted ventilation system is fitted as standard. It draws in air via a grille immediately behind the signalling window, and Grant reports that there have been no complaints about its effectiveness over the summer. Heating is from perimeter radiators at floor level.

Interior is welcoming, with cantilever seating aiding cleaning; McGill's logo stitched at Mannheim factory Interior is welcoming, with cantilever seating aiding cleaning; McGill’s logo stitched at Mannheim factory


Driver comfort

The Citaro’s cab environment is first class, and includes a number of aspects usually found only in coaches. The air-sprung seat adjusts extensively, and a development on Euro 6 models sees the steering wheel and instrument binnacle adjust as one unit.

Access is via a door which lacks a manual latch. Instead, it is held closed magnetically, removing a common source of rattles. The door is released via a dash button; McGill’s buses lack anti-assault screens, although if they were fitted reaching the button from outside the cab may be awkward.

The cab door also has a mechanism which moderates the rate at which it can close, preventing slamming. Within the door is a large storage space for the driver’s bag.

Visibility is excellent. Large external mirrors are fitted, but they are tight to the bus, removing much of the risk of damage. The internal mirror is large, and attached to the above-windscreen bulkhead.

An electrically-operated windscreen sunblind is complemented by a manually-lowered blind over the heated signalling window.

Cab heating and cooling is controlled by a handful of dials, with a variety of vent locations ensuring that the driver is comfortable regardless of the outside temperature.
Cab layout and comfort is excellent, with some coach-like aspects present Cab layout and comfort is excellent, with some coach-like aspects present



As fleet flagships on the Clyde Express services, the Citaros are worked hard and cover significant mileage. Average speeds are high; the powerful OM 936 is well up to the task, and makes easy work of what is asked of it.

ZF’s EcoLife does its best to keep engine speeds as low as possible, and in normal driving on level roads the tachometer seldom approaches 1,500rpm. On steeper sections its topographical-sensing software makes its presence known, and gears are held longer.

Doing so makes a noticeable difference. Although the OM 936’s peak torque builds from 1,200rpm, it really comes to life from around 1,400rpm onwards, producing an aggressive growl as it does so.

Hill climbing in such circumstances is spectacular, as demonstrated when returning to the Gourock depot. From almost a standing start at the foot of the very steep Larkfield Road the Citaro quickly accelerated to 30mph with ease, and would have done even better had it not been baulked by a van.

Equally, accelerating uphill out of a 30mph zone showed the OM 936’s strengths, while on a section of dual-carriageway the Citaro reaches its legal 60mph maximum easily. At the other end of the spectrum, it is happy to trundle along at around 800rpm at times of low power demand.

Ride quality and noise levels are both akin to those of a coach, and the bus is very well poised both during normal driving and when pushed hard on interurban sections. It is smooth, quiet and capable of making excellent progress, while the driver will be reassured by pedals which deliver excellent feel.

OM 936 engine is horizontally mounted at extreme rear nearside OM 936 engine is horizontally mounted at extreme rear nearside



McGill’s is an established Citaro operator and now has 45, including 10 articulated examples. While the Euro 6 buses have been purchased to upgrade the Clyde Flyer routes, Ralph explains that an 18,000kg GVW type gives benefits over lighter models in terms of standing capacity, an important consideration on some routes.

A slight fuel penalty comes as a result, although substantially less than may be expected. The Euro 6 Citaros weigh in at a respectable 10,775kg unladen, and on the Clyde Flyer routes they are returning highly respectable figures.

“The Euro 6 buses use around 10% less fuel than earlier Citaros on comparable duties, and deliver around 9.5mpg, which we regard as excellent,” says Ralph.

Although that may partially be explained by their interurban use, McGill’s has also trialled a pair on one of its Glasgow urban services. There, the return was around 9mpg, he says, comfortably exceeding expectations. Ad-Blue consumption is in the region of 30 litres per week.

“The Citaro is a quality product, and we would not hesitate to take more in the future if and when a requirement exists. It is considerably more expensive than lighter single-deckers, but on work such as the Clyde Flyer routes that extra investment is well worth it.

“It also does great things for our image. People notice the Citaros, and the Mercedes-Benz badge is an acknowledged hallmark of quality.

“We expect long lives from the buses; ideally we will run them on flagship routes for five-seven years before moving them to easier work, and we anticipate using them for their full lives. The truth is that they’re too good to sell on the second-hand market.”

With one or two teething problems having been dealt with rapidly under warranty by EvoBus, the Citaros have settled down and are liked by staff and passengers alike. On the Clyde Flyer route, they are also helping drive the Holy Grail of rising passenger numbers.

Whether the Citaro’s economics would stack up against a lightweight bus on a low-speed, moderate demand urban service is debatable. But in the interurban application, the combination of fuel economy, passenger appeal and a high standard of finish sets a benchmark for others to aspire to.

Facts and figures