Features: Magazine | Literary Review | Life | Metro Plus | Open Page | Education Plus | Book Review | Business | SciTech | NXg | Friday Review | Cinema Plus | Young World | Property Plus | Quest |

Where’s the smoke?

TESTDRIVE The BlueTEC Mercedes dispels myths about diesel, says SHAPUR KOTWAL

Diesel — the name evokes images of smoke-spewing, heavy and crude vehicles whose only benefit is lower running costs due to diesel being cheaper than petrol. But that is not the case anymore. Modern-day diesels are as good, if not better, than

their petrol cousins in all respects. And if you’re driving diesels in a place which has a history of not being too kind to diesels, you know that diesels have indeed come a long way. We’re talking about Vermont, the U.S. state that, along with California, has traditionally been super-strict on diesel cars.

We’re in pristine hills not too far from the Canadian border, driving a bunch of big, heavy diesels from Mercedes. But these are not your ordinary Merc diesels. Okay, the CDI common-rail diesel motors under the hood are basically the same. But Merc has carried out a set of modifications and fundamental exhaust after-treatment changes that together allow these diesel engines to be less polluting than a petrol motor. According to U.S. law — they must adhere to the same basic petrol engine emission norms despite having a totally different emission profile.

So while diesel engines produce far less carbon monoxide, carbon dioxide and hydrocarbons than petrol engines, they have to be worked on to attain petrol engine-like particulate and nitrogen oxide emissions. While this loads the deck in favour of petrol-engine cars, diesels that can be made to adhere to the U.S.’s Tier 2 Bin 5 norms are much cleaner cars overall, with emission standards at par with even some petrol hybrids.

The special equipment used on the BlueTEC M-Class I’m driving includes a particulate emission trap as well as the now common oxidation catalyst. In addition, there’s the AdBlue or urea tank (from which these Mercs get their name), housed in the rear of the car, that helps reduce NOx (oxides of nitrogen) emissions. Liquid urea is added to the exhaust tract and is then stored in the SCR (Selective Catalytic Reduction) catalyst in the form of ammonia. This ammonia then combines with the nitrogen oxide released by the engine that produces harmless nitrogen (this car doesn’t use a De-NOx catalyst like the BlueTEC cars in Europe).

From behind the wheel, however, you simply have no idea that you are sitting atop a really hi-tech, electronically controlled chemical plant. Everything functions as normal; there are no extra controls, no warning buzzers and no flashing lights. The AdBlue tank needs to be topped up at service intervals, but this is a simple procedure, similar to topping off other fluids in the car. Take the BlueTEC badge off, and you’ll think this is a normal M. That said, initial throttle responses on the 210 bhp diesel did feel a bit dull, before the SUV really takes off, making full use of that 55 kgm of torque.

Length/ Width / Height:

4780/1911/1815mm

Wheelbase: 2915mm

Turning circle: 11.75m

Engine: V6, 2987cc, diesel

Installation: Front, longitudinal

Power: 210bhp at 3400rpm

Torque: 55kgm at

1600-2400rpm

Printer friendly page  
Send this article to Friends by E-Mail