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quite there yet...
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Mercedes-Benz's latest hybrid Atego is waiting to step out into the spotlight. There's interest in it, for sure, but not enough firm orders...
Words: Brian Weather-ley Right nowp hybrid trucks are the classic case of the chicken and the egg. Well, that's certainly how Karl Deppen, director for life-cycle management at MercedesBenz Trucks, sees it. As project leader for the latest Atego hybrid 12-tormer, his team has developed a viable diesel-electric, parallel-hybrid version of Mercedes' popular rigid. However, despite some interest, the hybrid market still hasn't reached that vital tipping point when operators stop looking and start buying.
"As long as the volumes are low, it's going to be hard to sell hybrids," reports Deppen. "If we don't have the demand, we won't get the production costs down. If we can't get the costs down, we can't get the volumes." How small, though, is anyone's guess. Even Deppen can't predict the potential hybrid market in Western Europe, although a 'white knight' could he riding to the rescue in the unlikely form of the London Low Emission Zone. As demand to improve air quality in European cities grows, hybrid sales could take off as the big logistics fleets look to reduce both their carbon footprints and cut their fuel costs."London has been leading on low emissions; I imagine other cities will follow," Deppen says.
Evaluation prototypes
Daimler has more than 600 Mercedes, Mitsubishi Fuso and Freightliner hybrid trucks currently in operation worldwide, including 10 Canter Eco Hybrids running in a three-year UK trial with operators such as Tesco, Royal Mail and TNT (CM 21 August 2008).
More recently, Mercedes delivered five Atego hybrids to DHL/Deutsche Post, which Deppen describes as: "Evaluation prototypes that will enable us to gain some experience and understanding of the systems, so we can optimise them for the vehicle. We need to get feedback from the customer and an understanding of the blending of the e-motor with the diesel engine." Notwithstanding any major setbacks with the Atego project, Mercedes is looking to set up a limited production run around the end of next year in order to provide more hybrid trucks for customer trials.
"It's not a 'series production"; maintains Deppen, "but we want to get to the next step and provide vehicles to customers who want to reduce emissions, noise and CO."
Mercedes, meanwhile, is quoting potential diesel savings of 10% to 15% using the Atego's hybrid drivetrain. Against that, there's the additional 400kg-plus of lithium ion battery pack and hybrid drivetrain, plus the complexity of the system. But the extra cost of `hybridisation' — estimated by Deppen as anything between 30% to 50% — is the biggest disincentive to fleet buyers.
"At the moment, there's a significant price difference between a hybrid and conventional truck," he reveals, "and we need to find customers who are excited about reducing fuel and emissions. In the passenger car sector, more people are buying out of conviction; a truck firm needs to make money with its equipment. With the Atego hybrid, we've not yet hit the magic point in the cycle."
Very little difference
Having driven the 7.5-tonne Eco-Canter last year, we were keen to compare one of DHL's 12-tonne Atego `BlueTec' hybrids with it. Last month we got the chance to do so around a short inner-city circuit in Stuttgart.
In addition to the 44kW AC `e-motor" fitted between the clutch and the transmission, our truck was also equipped with M-B's Motor Stop/Start (MSS) system, which turns off the diesel engine when the truck is stationary to stop excessive idling, and, for the first time, an automated version of the standard Atego six-speed manual box.
From the outside there's little to distinguish a hybrid 1222 from its diesel-only cousin, apart from the extra radiator on the chassis, which cools the inverter and motor. There's no change to its dash or interior.
With most fuel consumed during acceleration from rest, the hybrid Atego uses its electric traction motor and battery power to get the truck moving to around 15mph to 20mph when the 'regular' 218hp four-cylinder diesel engine takes over the main propulsive effort.
After that, it's pretty much conventional driving. With 420Nm of torque available from rest from the e-motor, the hybrid's acceleration is brisk right up to the point where the diesel kicks in and beyond. You don't feel any noticeable power transfer or 'jerk' in the transmission as the e-motor runs down and the main engine takes over.
Despite carrying a full 5.1-tonne payload, our hybrid Atego showed no loss of performance throughout the speed range. Pulling back to our start point and turning the diesel engine off, you can hear the cooling fan for the battery and inverter. Otherwise, we defy anyone to spot any difference in driveability between a conventional Atego 12-tonner and its hybrid sibling.
More changes to come Looking at the special schematic display fitted in our truck for demonstration purposes, we could easily see when the e-motor was contributing to the truck's initial propulsion. Likewise, when running downhill on a local motorway at a steady 80km/h, the laden truck was soon recharging the battery pack with its regenerative braking.
While light midday-traffic volumes in Stuttgart meant we didn't get to experience the MSS function, we can see its attraction in dense city traffic.
We were less impressed, though, by the Atego's six-speed automated transmission, which showed none of the intuitiveness of the current Powershift dedicated two-pedal auto available on the Actros.
Climbing hills around Stuttgart, we found ourselves having to prompt an upshift manually when the box insisted on holding a lower gear with noticeably higher revs. Mercedes says "there are more developments to come:which should see a fully-dedicated auto (rather than an automated manual) box becoming available further down its product weight range. al