We’ve just driven Mercedes-Benz’s important new eco-specialist C-class: the – take a deep breath – C250 CDI Blue Efficiency Prime Edition. Putting the Transformers jokes to one side for a second, listen up because under the bonnet lies the beating heart of a concept car. The C250 CDI’s Blue Efficiency turbodiesel engine cropped up earlier this month as the motive power for the Fascination concept car, the wacky future E-class shooting brake styling model from the 2008 Paris motor show.
But there’s nothing wacky about a C-class with 201bhp, a 155mph top speed, and emissions of just 138g/km CO2 despite full-fat equipment levels. If the C250 CDI Blue Efficiency is the torque-rich route to an environmentally friendly future, count us in…
Ok, so the C250 CDI Blue Efficiency is an eco model. What’s this torque-rich business?
Right, stay with us for a second while things get technical. Mercedes’ new ‘250’ CDI engine is actually an all-new 2.2-litre inline four, with twin sequential turbochargers and the latest in common-rail piezo injection. The cylinders are 4mm closer together, making the engine more compact, while mounting the crankshaft on one side allows for pedestrian impact friendly, angled installations.
A small, high-pressure turbo acts alone initially to boost low-speed response, gradually handing over to a larger, low-pressure turbo as the revs build, ensuring smooth, lag-free acceleration. The piezo injection operates at a huge 2000 bar – just like Audi’s Q7 V12 TDI – and is twice as precise as before to squirt exactly the right amount of fuel at exactly the right time. Want not, waste not…
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The general Blue Efficiency modifications aren’t so surprising: longer gearing, low-rolling resistance tyres, underbody cladding, aero-mirrors, power steering that disengages when not in use, a new dash display with a fuel consumption bar-graph and a sixth-hungry gearshift indicator.
Yet being based on the high-line Europen Avantgarde trim level means this car isn’t exactly short of standard equipment. Despite this heft, the green C250 CDI officially returns 54.3mpg combined. And concentrating an unusually large amount of the engine’s capacity in the stroke (99mm, compared to 83mm for the bore) helps these innovations generate a ridiculously muscular 369lb ft of torque. Which arrives at just 1500rpm. Isn’t technology wonderful?
So what you’re saying is, this is a performance car masquerading as an eco model?
Not quite. Since the C250 CDI will happily pull from at least 500rpm lower than its torque peak in third, you pretty much never need to change gear around town. The 0-62mph sprint takes 7.0 seconds. But it’s the mid-range response that really makes your brain melt.
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Tackle a gentle roundabout in, say, fourth gear, pin the throttle without downshifting and wave bye-bye to your stomach as the engine ramps all the way up to 5000rpm without flagging. Its pick-up, as the Blues Brothers would say, is seriously impressive. Get aggressive mid-bend and you’ll soon see the traction control light flashing; on-gas adjustability is not an issue. And who thought we’d ever say that about an eco special?
It can’t all be good, surely?
You’re right. Although this new engine is almost as powerful as Mercedes’ 3.0-litre V6 turbodiesel – and more efficient – it can’t match its refinement. The C250 CDI is by no means awful, but it is a touch noisier than we’d like, and passes a few vibrations through to the cabin. This is partially to do with the torquey engine design.
The six-speed manual gearbox is notchy (an auto is coming in 2009), the steering a little vague, and the C-class’s interior quality still lacks a certain something. But worst of all is the ride. The Euro-spec Prime Edition includes Mercedes’ Agility Control automatic dampers, which simply turn the ride all jittery. Not so smart.
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Just one more thing: that Prime Edition name?
Ah yes: Prime Edition… This denotes the initial limited run of 5000 C250 CDIs, which include special trimmings (bespoke Prime Edition floor mats, anyone?). This is for Europe only, however, as the UK won’t get the C250 CDI until summer 2009. The engine will then start appearing elsewhere in the Mercedes line-up – including the all-new 2009 E-Class and E-Class Coupe – before being joined by lower-powered variants.
Verdict
We came to test Mercedes latest efficiency innovations, and came away stunned by the accompanying flexibility and torque of the C250 CDI. And if you aren’t entirely convinced about its fuel consumption credentials, consider that this is a fully specced Mercedes saloon, not a stripped-out econobox hatchback.
No word on pricing yet – the Prime Edition costs €40,638 (approximately £31,800). Who knows what will happen between now and next year in the switch to right-hand drive. But this car, like BMW’s 123d, proves you can have your eco break, and burn rubber, too.