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By CJ Hubbard
15 October 2008 09:14
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...
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...Click 'Next' to read the rest of our Mercedes C250 CDI Blue Efficiency car review
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motortrend says
RE: Mercedes C250 CDI Prime Edtion CAR review
muy lindo auto y lindo de afuera como todo lo de Mercedes Benz.
23 October 2008 05:43
revcounter says
Subaru makes a convincing argument about the straight load paths their pistons take in an opposed engine. Mercedes' effort at rearranging the crankshaft sounds inferior. I also would worry about the complexity of this Mercedes engine. Turbochargers are notoriously short-lived. Are two absolutely necessary? And in 2008 why is anybody needing to skimp on cylinder wall thickness to fit a four cylinder engine into a car that size? Can't help noticing the date again when I read they are releasing the engine without de-bugging the rest of the powertrain. There's a second tier manual and we have to wait for the automatic. Mercedes pride prevents them from licensing Honda's urea-free NOX system. They expect you to endure the car refusing to start every 12,000 miles if you can't find the blue nectar.
19 October 2008 16:58
Batty says
Thank you Tim & CJ, but I still don't think that the crankshaft is offset. Does he mean the camshaft instead? An offset crankshaft would mean a real change in bottom end engine philosophy, whereas an offset camshaft is more probable. Sorry to be a nerd about this but I am intrigued by the detail. You only have yourself to blame, your site encourages we anoraks!
16 October 2008 20:50
TimPollard says
Quick update from C.J. This engine is key to Merc's new cleaner plans. There will be an even more economical 170ps twin-turbo version and a single, multi-vane 136ps variant shortly. The engine will also appear in the GLK, E-Class, E-Class Coupe, Sprinter vans, etc. And the various eco technology developed for the BlueEfficiency models is already being fed through to standard models as production capability allows (door mirrors and undertrays on every C-class being the first examples).
16 October 2008 16:48
A question, not a crticism, how exactly does "mounting the crankshaft on one side allows for pedestrian impact friendly, angled installations." work? The crankshaft on any conventional engine is co-planar with the piston movement, not offset. Correct me if I am wrong. engineer your field of expertise I recall, any thoughts?
16 October 2008 02:24
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