Mercedes-Benz has revamped the Sprinter in a bid to outflank its rivals and emphasise its environmental credentials. From July onwards all models will meet the tougher, Euro 5 exhaust emission rules.
That’s despite the fact that the regulations as they affect light commercials grossing at up to 3.5 tonnes don’t come into force until 2011. They do, however, affect vehicles grossing at above that weight from this autumn onwards, and Sprinter is marketed at gross weights of up to 5.0 tonnes.
The key weapon in Sprinter’s Euro 5 armoury is its all-new 2,143cc OM 651 four-cylinder diesel. Replacing the old 2,149cc unit, it’s up for grabs at 95hp, 129hp and 163hp, with torque ratings of 250Nm, 305Nm and 360Nm respectively. The top variant benefits from an eight per cent hike in power output and a 10 per cent torque boost when compared with its predecessor.
A long-stroke under-square engine with a compression ratio reduced from 17.5:1 to 16.2:1, the four-cylinder offers smooth idling even when cold contends Mercedes. Common rail fuel injection is fitted with pressure increased to 1,800 bar along with solenoid injectors with a seven-hole injection nozzle.
It allows up to five injections per combustion cycle. A maximum of two pre-injections is followed by the main injection plus a post-injection phase if required. The benefits include a gentle increase in pressure and therefore quiet, smooth, running Mercedes says.
As a further aid to smoothness, the engine is equipped with what are known as Lanchester balancer shafts; two counter-rotating shafts that turn within a cassette below the crankcase and are driven by crown wheels. Mercedes reckons that it’s the first time they’ve ever been used in a van.
The arrangement is named after pioneering British automotive engineer Frederick Lanchester, renowned among other things for his work on reducing vibration in car engines in the late 19th century.
The least powerful version of the new engine gets a single-stage turbocharger with variable turbine geometry. However, its stablemates come with a two-stage turbocharging set-up, a development of the package deployed in the newcomer’s predecessor. It involves a small high-pressure turbocharger working in conjunction with a big low-pressure turbocharger. The two turbines are connected in series.
At low engine speeds only the small one is active, allowing a high charge pressure to be built up quickly to boost responsiveness. At high engine speeds the bigger one kicks in, aiding motorway performance.
A bigger intercooler has been installed across the range offering 20 per cent more cooling performance. That helps boost power output.
While some heavy truck engines need something known as Selective Catalytic Reduction in order to achieve Euro 5 — it requires the addition of a urea-based liquid known as AdBlue — that’s not the case with OM 651. An admittedly sophisticated water-cooled EGR (Exhaust Gas Recirculation) system is sufficient, without the need for anything else to be added.
So how do we know all these details? Partly because of the extraordinary 3D image of OM 651 projected into the middle of a crowd of journalists at the company’s van technology centre in Stuttgart, Germany. It allowed the engine and its internal workings to be inspected from all angles and specific areas — the EGR set-up for instance — to be examined in detail. “In fact we build the entire vehicle in 3D on our computers before we do anything else,” says van technology head of development, Dr Sascha Paasche.
At the top of the power output scale, the V6 OM 642 2,987cc diesel has been retained, but re-engineered to meet Euro 5. Power output is up slightly, to 190hp, while torque is up by 10 per cent, to 440Nm.
Mercedes reckons that the new engine will burn up to 1.5 litres less diesel every 60 or so miles than its predecessor, while the OM 651 should burn from 0.5 to 1.0 litre less. CO2 emissions are driven down too as a consequence.
Six-cylinder or four-cylinder, a particulate trap comes as standard. Operators on stop-start city centre distribution work may fear that it won’t get hot enough to purge itself, but Mercedes reckons that the occasional high-speed blast up a dual carriageway should be sufficient to deal with the problem.
The new and revised engines are married to a new ECO Gear six-speed manual gearbox, with a low-ratio first gear and a high sixth. Two versions of the ’box are on offer; the 360 for the four-cylinder engines and the heavier-duty 480 for the V6.
One or two other changes have been made to Sprinter, primarily revolving around safety. Adaptive brake lights have been installed that flash rather than merely illuminate under heavy braking. What’s more, if a customer has asked for his vehicle to be fitted with a trailer coupling at the factory then Sprinter’s ESP will be set up in such a way that it will kick in if the trailer starts to snake.
Still with towing, the maximum permitted towing weight of many Sprinter 3.5-tonners has been increased to 3.5 tonnes.
We set off in a 313CDI van powered by the 129hp version of the OM 651. Running quietly and smoothly, our Sprinter pulled away strongly from rest and showed plenty of mid-range get-up-and-go too, but what really impressed us was the amount of punch it packed in fifth and top. With plenty of torque on tap right the way across the rev range, an impressive degree of flexibility meant that there was no need to keep changing gear in order to get the best out of the vehicle.
That was just as well, because the change offered by the ECO Gear ’box was somewhat clumsy, lacking the smoothness and precision of, for example, the ’box in the new Ford Transit Connect we tested recently.
Even though it lacks the twin-turbocharger set-up enjoyed by the more powerful variants, the 95bhp version of the OM 651 we sampled in a 310CDI dropside was no slouch either. Yet it too suffered from a mediocre gearchange as did the 163hp 516CDI we drove.
An excellent performer otherwise, it is alas hampered by the mandatory 56mph speed-limiter fitted to all new commercial vehicles grossing at above 3.5 tonnes.
All three Sprinters boasted highly responsive steering plus all the other Mercedes virtues, including unimpeachable build quality.
Prices had yet to be released at the time of writing. Mercedes states, however, that some of the new Sprinters will be roughly £300 cheaper than the equivalent current models, and some will be around £400 more.
Smooth, quiet and powerful, the new four-cylinder 2.1-litre OM 651 Euro 5 diesel now being deployed in Mercedes-Benz’s Sprinter is without doubt an impressive piece of engineering. It seems a pity therefore that it was let down by an at-times-stodgy gearchange courtesy of the new ECO Gear box. All the other Sprinter virtues remain intact, however, including good looks and rock-solid build quality. Sort the gearchange out and we’ll be happy to give the Three Pointed Star’s new offering an unqualified thumbs-up.