Electrification perfection?

 

 

 

 

 

 

 

 

 

 

The Mercedes-Benz eCitaro made its UK debut at ITT Hub in June of this year. Richard Sharman takes the very first example for a drive to see if this three-pointed star is as good as its diesel forerunners

A premium brand in any industry means that you have certain expectations when you interact or use that brand’s product. With more than 55,000 units sold worldwide, the Mercedes-Benz Citaro is one such product that you would expect to be better than anything else you have experienced before.
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Two decades of Citaros

It is hard to comprehend that it was 21 years ago that the very first batch of right-hand drive Mercedes-Benz Citaros entered service in the UK with First Manchester, on W registration plates. The very first example to arrive in the UK, W179 BVP, still survives today and is safely in preservation with Johnny Eaves. The rest of the First Manchester examples were not so lucky and headed to Barnsley.

However, what is impressive is that many of the early examples are still in service today, First Worcester has an allocation of 23 examples dating from 2002 to 2007, whilst the Go-Ahead Group has a large number in use of varying ages, proving the longevity of the product.
I attended the launch of First Worcester’s Nimrod-branded 2002 examples in April 2019, and with refurbished seats, a new coat of paint and private number plates the general public would be hard pushed not to mistake these examples for much newer vehicles.

My own personnel experiences of the Citaro were also of very early UK production examples: X438/9 KON were owned by Warwickshire County Council, but operated by Guide Friday. In May 2002 EnsignBus took over Guide Friday and the two Citaros moved over to the Stratford Blue operation.

Back in 2002, the Citaro was in a different league to many other models that were on the road at the time. From a passenger perspective, it looked modern and had an interior that looked years ahead of the competition. But the revelations did not end there. From a driver perspective, it had one of the best driver environments seen – and not only that but it had an electric cab window, electric mirrors, and a steering column that could be adjusted to your liking. Many of these features were unseen in a city bus at the time, but the good news didn’t end there. It was also nice to drive, with a good turning circle and good handling.

Whilst I may sound like I am being a tad nostalgic, what I am saying is that nearly 20 years ago it was a good product. It set the bar high. I have not driven a Citaro since 2004, so my expectations of the eCitaro are even higher. Has that original Citaro DNA been kept and improved on, or is the new generation a different vehicle altogether?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Next generation city bus

The Mercedes-Benz Citaro range offers multiple variants of body length, capacity and power, many of which can be seen in-service throughout Europe, but in the UK and Ireland, the most common recent new vehicles have been the standard Citaro, the articulated Citaro G and the short Citaro K. These are powered by a diesel Mercedes-Benz engine that has become well known since the introduction of Euro VI emissions regulations, the OM936, driving through a Voith gearbox. The ability for the Citaro to be 100% zero-emission and powered by electricity was a good enough reason for Mercedes-Benz to release a new generation of Citaro that would see new styling to take it into the 2030s and beyond.

The bus industry’s first look at the eCitaro was at its world premiere at the IAA Commercial Vehicle Show in Hanover, Germany in 2018. European operators started taking delivery of the new model immediately after. The UK has had a long wait in comparison.

Neil Gladstone, eCitaro Project Sales Manager told CBW: “The eCitaro demonstrator we first showed at ITT Hub is the first right-hand-drive version to arrive in the UK and is Generation One. Operators can order the eCitaro today and those vehicles will be delivered in 2022 with Generation Two battery technology, offering increased kilowatts per hour. The eCitaro has been designed so that as the generation of Citaro moves on over time, operators will be able to replace the batteries with the latest generation when they require changing. Twelve batteries in total are fitted, four located where the engine would have been and eight situated on the roof. In single door format, the eCitaro can carry 39 seated passengers, with 27 standees. There is also an option to specify the vehicle in dual-door format.”

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

First impressions

Looking from the side and rear you can tell that this new model is very much an evolution of the Citaro. However the front end has a more radical look that is much sharper but still leaves no doubt that this is a Mercedes-Benz product. It is almost as if the appearance of the whole vehicle radiates from the extra-large three-pointed star that sits proudly on the front of the bus. Two thick chrome-effect slats with design elements accompany the logo and then angle up as they pass over the top of the headlights. Interestingly a second smaller badge is mounted above it that features Daimler’s Mercedes star in Benz’s laurel wreath which first appeared on 18 February 1925. A nice and fitting design feature that marks the start of a new generation.

Operators will be pleased to know that the front bumper is still split into three sections for ease of repair, should a corner panel need replacing due to accident damage. The headlights mark a significant change for the Citaro, which have always been oblong-shaped. The eCitaro sports dual Hella units, with the outer unit being the LED headlight and the inner unit featuring LED daytime running lights at the top and indicators at the bottom. Front fog/cornering lights are also fitted. The radar for the Preventative Brake Assist (PBA) system is located in the centre of the front panel, above the number plate. The curved windscreen leads up to a dropped roofline that sits over the very top of the windscreen.

Comparing the eCitaro from the side with a standard diesel UK version you find, reassuringly, that the glazing and panels appear to be identical. This is highly beneficial for operators that may already be operating the diesel version, in that existing stock could be used for any window replacement. The deep-tinted glazing that follows the lines of the flared wheel arches is a nice touch.

Any panel damage caused whilst on the road can be easily fixed thanks to four removable panels between the axles; two skirt panels and two centre panels. Two opening panels are fitted behind the rear axle.

The roof superstructure that contains some of the vehicle’s batteries and the air-conditioning system has been neatly concealed behind a roof-edge ridge.

The rear of the eCitaro is the least unchanged in terms of styling, it retains its practical three-piece rear bumper, smart LED rear light cluster and reversing camera. The superstructure trim, as on the front of the eCiatro, does cover the very top of the rear destination glass.
Careful consideration will need to be taken when applying corporate liveries to the eCitaro, as there are many large windows. However, some slight tweaking or a type-specific livery will solve that issue.

Interior quality

Stepping through the wide entry doors of the eCitaro and over the manual, folding, 350kg-capacity wheelchair ramp you are greeted by a light and airy interior. The cantilever seating plays a huge part in creating a clear and unobstructed saloon floor, and also makes the vehicle much easier to keep clean as there are no dirt traps.

The eCitaro marks a general update of the interior of the whole Citaro range. A feature that Mercedes-Benz is very proud of is the coffered ceiling design with its sweeping roof-edge flaps to the sides. The air circulation system is built into textile ducts in place of the current plastic air ducts.

Another update is the saloon lighting. Rather than running the entire length of the vehicle, the brand new LED lighting modules now act as connectors between the roof-edge flaps. The light of the LED lamps is refracted and makes the lighting efficient at all times of the day and night. Additionally, the vehicle’s loud speakers are incorporated into these units, for use with the driver’s public address system, if specified, and the sound of the bell when pressed. The bell push, a design success in itself, has had a lot of thought put into making it a feature of the vehicle, rather than a function.

Due to the uncluttered saloon floor and seemingly cavernous amount of interior space, wheelchair access from the entry door is as it should be: easy.

The standard seat in the eCitaro is the City Star Eco, although two further options are available for longer inter-urban routes. The demonstrator was also fitted with illuminated USB ports by each seat. At the rear of the vehicle, as in the diesel version, some space for seating is lost due to the positioning of fans and batteries where the engine would normally be. However, the eCitaro still manages to seat a respectable number of 39 seated passengers.

Overall, the interior of eCitaro delivers the premium feeling you would associate with the Mercedes-Benz brand.

 

 

 

 

 

 

 

 

 

 

 

Thermal management

There are two things to consider when developing an electric bus: First is maintaining the battery temperature and second, how to heat and cool the saloon. Mercedes-Benz has addressed both issues by developing smart thermal management systems that keep the batteries at an ideal temperature. Cold batteries can reduce range and performance, so this system always ensures that they are kept at the correct temperature which maximises charging capacity, performance and range.

In terms of saloon heating and cooling, the eCitaro boasts a system that is capable of pre-conditioning the vehicle for service whilst on charge. This means that the eCitaro will always be ready to go for its next duty, no more window scrapping during the winter or starting with a hot bus in the summer. Not only is this convenient for the drivers and passengers, but also means an eCitaro leaving the depot in the morning will not need to waste battery energy working hard to get the vehicle to the desired temperature, thus increasing the range and longevity of the battery.

Battery technology

The batteries that power the eCitaro UK demonstrator are Generation One technology. Production examples will feature Generation Two technology. Speaking in Mercedes-Benz Omnibus magazine, Gustav Tuschen, Head of Development at Daimler Buses explained the battery options available and the new solid-state batteries: “What we are talking about here is the second generation of Nickel, Manganese, Cobalt (NMC) batteries, to be precise: Lithium Nickel Manganese Cobalt Oxide Cells. Their energy capacity has leapt forward by around a third, from 24kWh to 33kWh per module. The maximum of 292kWh of energy capacity in a bus has become 396kWh. This enormous step forward will allow a correspondingly larger range. And there’s more: as not only the geometric shape but also the battery terminals are identical, transport companies can upgrade any eCitaro they already own if they need to and increase their performance further.”

The 12 NMC batteries fitted in the UK demonstrator have an overall capacity of 292kWh, which means, condition-dependent, the eCitaro has a range of around 170km. Production examples fitted with Generation Two technology will see the battery capacity increase to 396kWh, this boosts the range further to around 270km.

In addition, solid-state battery technology is an option, as Gustav explained: “With the solid-state battery, we are initiating a technological revolution. In putting it in buses, we are powering ahead of the competition. Our customers can profit from an unprecedented technology. The energy density is even greater still, the service life longer. And not least, a solid-state battery works at around 80°C. This temperature is obtained during driving operation from the energy produced during discharge. This means cooling the battery is not necessary. Finally, solid-state batteries have no need of nickel, manganese or cobalt.”

Gustav continued by explaining why Mercedes-Benz will offer both battery options: “Even the solid-state battery cannot work magic. ‘One size fits all’ just doesn’t do it as a motto. The solid-state battery is only limited in its rapid charging ability. So if you want intermediate charging, say, via pantograph while en route or during a depot stop, you are better off with NMC batteries. That is why we offer both: our customers get to choose.”

First generation solid-state batteries are expected to increase energy capacity to 441kWh and range to 320km.

Charging of the eCitaro UK demonstrator at EvoBus in Coventry, where it is based, is via a EKOEnergetyka charger which can be plugged into the CCS2 charging connector on the offside over the front wheel arch, or at the rear of the vehicle to the left of the energy bay, where a door has been installed in the boot lid for ease of charging. Depending on how strong the available DC charger is, it can take between one and a half hours to three hours to charge from 0%. All electrical operating systems are constantly monitored, and operators can take advantage of Daimler’s Omnibus On, which monitors 30 components and functions and report them back to the operator.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Driver comfort

The cab of the eCitaro (or driver’s workstation as Mercedes-Benz prefers to call it) has changed little in this new incarnation, which is fine with me as it has always had one of the best working environments for drivers. For security, the cab door is magnetically locked, and can be opened by pressing the release button on the left side of the dashboard. Once sat in the comfortable Grammer air-suspended driver’s seat you will find it has plenty of adjustment and goes back a long way. The steering column and dashboard is also adjustable for height and angle. All-round vision is superb thanks to narrow A and B pillars, whilst an electrically operated and heated sliding cab window is a nice addition. The Mobitec ICU402 control unit and controls for saloon heating and air-conditioning are mounted above the driver’s head whilst the CCTV, which is linked to the reversing camera, sits above the dashboard.

A feature that impressed me is that the driver has their own air-conditioning fan, which sits under the CCTV monitor and has two vents. A key ignition system is fitted (switched ignition and ‘ready’ button options are available) and is hidden to the left of the driver’s seat, low down and out of view. The handbrake is situated within easy reach of the driver’s seat. Door and suspension controls are fitted to the left of the dashboard and the lighting to the right. The view of the binnacle through the multi-function steering wheel is clear.
Driver safety is clearly important to Mercedes-Benz as the cab has front impact protection based on the pendulum impact test under the European ECE R29 standard.

On the road

Sitting behind the wheel of the eCitaro took me back to 2004, and the last time I drove the type. Even after all these years, it has that familiar feel and a view from the cab that has stood the test of time. The narrow A and B pillars, the quarter light windows and the large windscreen that offers an uninterrupted view of the road ahead. However, there was one thing missing when I turned the key, the familiar noise of the Mercedes-Benz engine!

Instead, the start-up is a fast and silent one, with the vehicle ready to go in seconds. Departing EvoBus, Coventry on a full charge, the plan was to take it on a mix of roads towards and around Stratford-upon-Avon to see how it performed.

Pulling away from EvoBus and onto several roundabouts it is fair to say that you are aware of the extra height and weight when you first start driving it, and although the handling still very much has the familiar Citaro feel, you still take roundabout slightly easier.
The electro-hydraulic steering is a joy in operation and perfectly mimics a conventional steering system. It is still well-weighted, as you would expect. Acceleration from the ZF AVE 130 electric portal axle with electric motors at the wheel hubs makes the eCitaro swift drive, and with no gears, better than the diesel version. Power has been restricted though, to ensure a smooth ride for passengers, as torque is instantly available. The peak output of the motors is 2x125kW, whilst torque is 2x486Nm.

I was now settling into the run on the A46 towards Stratford-upon-Avon, and found that I was enjoying the drive and the satisfying noise that the ZF electric motors made when pulling away!

One feature of the eCitaro is the ability to coast the vehicle, so regeneration does not occur until you start applying the foot brake. The driver is fully aware of when the vehicle is using power or regenerating thanks to the fitment of the power meter in place of the RPM gauge. The needle sits in the middle of the meter; when you brake it moves to the left and when you accelerate it moves to the right. This can be seen in the test drive video that accompanies this feature on our YouTube channel.

Arriving in Stratford-upon-Avon I took the eCitaro around our test route that takes in narrow lanes and country roads. The 12.1m demonstrator took the town in its stride and was extremely manoeuvrable in all situations presented to it. I even managed to get it around the small roundabout at the junction of Bridge Street and Wood Street twice without issue thanks to its decent steering lock. By this time I had been driving the eCitaro for well over an hour and had got used to the additional height and weight of the roofline, it became second nature to drive.

Sideguard Assist is fitted to the demonstrator. Its radar sensors monitor the lane to the nearside of the vehicle and if a moving object is in the monitoring zone to the side of the vehicle, a yellow LED triangle lights up at the driver’s eye level in the A-pillar on the left-hand side. If there is a risk of collision, the LED flashes brightly several times in red. It then remains permanently illuminated in red. The driver’s seat vibrates to underline this warning. This is a great feature and worked well around the town.

Leaving Stratford to head back towards Coventry we climbed the hill on A46 with ease at 50mph. Arriving back at EvoBus after 3hrs and 30 minutes of driving and some 50+ miles the eCitaro still had a charge of 68%, which I thought was good going when you consider that at least 42 miles of that time were spent at maximum speed with hardly any regeneration taking place.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In conclusion

The eCitaro is a well-built piece of futuristic technology that simply works for the passenger, driver, operator and most importantly, the environment.

Whilst its arrival has come towards the end of the first wave of electric buses in the UK, its wait should not deter from the fact that higher investment cost for route conversion will require a more ‘heavyweight’ build for extended operational life. In such a case, a late arrival may be fortunately good timing.
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