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By
EWAN KENNEDY
14 July 2008
Mercedes-Benz could be soon be moving well forward in the sales
race in the United States, thanks to its fascinating new range of
turbo-diesel powerplants.
While
fuel prices aren't as high in the USA as in Australia, typically
they are paying about $1.20 per litre for petrol and $1.32 for
diesel, the Americans’ big gas guzzlers are causing them real
pains in the pockets.
Mercedes
feels that someone trading down a size from a huge petrol-powered
SUV to a mid-sized Mercedes M-Class diesel can cut their fuel
bills in half. The savings in Australia wouldn’t be quite as
dramatic as we tend to use more sensible vehicles to start with.
We
have just spent a few days with on the other side of the Pacific
as guests of Mercedes-Benz to witness the German maker’s
expansion of sales of what can be described as the world’s
cleanest passenger car diesel engines.
California
has some of the toughest emission control regulations in the
world, something that doesn’t surprise anyone who has ever
witnessed Los Angeles on the numerous days when the mist rolls in
from the sea to combine with man-made smog. So Mercedes had the US
west-coast market very much in mind when it developed its latest
generation of turbo-diesel engines.
Using
a technology called BlueTec, which is already used on some
Mercedes commercial vehicles sold in Australia, these
new-generation passenger diesels are as clean as the best petrol
engines.
The
BlueTec system injects a special fluid called AdBlue into the
exhaust system of the 3.0-litre V6 turbo-diesel engine (the engine
with the ‘320’ in its model designation). Its purpose is to
reduce emissions of nitrogen oxide by around 80 per cent.
AdBlue
is an aqueous urea liquid that is firstly broken down into water
and urea by the exhaust heat. When the engine reaches the right
temperature the urea is converted into ammonia. The ammonia is
stored in a special catalytic converter and reduces the nitrogen
oxides to harmless nitrogen.
Though
the AdBlue fluid has to be added to a separate tank by the vehicle
driver at the time of refuelling in large trucks, the situation is
simpler in cars and SUVs. So low is the consumption, about a tenth
of a litre per hundred kilometres, that AdBlue tank only has to be
filled as part of the routine vehicle service at a Mercedes
dealership.
Note
that Mercedes sees BlueTec, and other add-on systems of its
emissions controls, as secondary stages in cleaning up the
engines. To the Germany company the primary stage should always be
cleanest engine design in the way of the best in turbochargers,
combustion chambers, valve shapes, piston design, engine
electronics, and so on.
We
have driven the new Mercedes BlueTec models in various formats.
Primarily in the M-Class wagons as these are the bigger sellers in
the range in Australia. We have also test driven the big GL-Class
seven seater SUV, as well as in the R-Class sporting wagon.
In
all cases the engine felt perfectly normal, with minimal lag from
the turbo system and plenty of torque – it peaks at 540 Nm
between a mere 1600 rpm and 2400 rpm – to make hillclimbing and
overtaking safe and simple. Though there's some additional engine
noise from outside the big Mercs compared to at petrol unit, the
in-cabin sound and refinement is virtually as good as that of a
modern petrol engine.
At
this stage the Mercedes BlueTec technology hasn’t definitely
been announced for importation to Australia in passenger vehicles.
Ever a company that likes to cross every ‘t’ and dot every ‘í’,
Mercedes in Australia has yet to finalise its business case on the
BlueTec units. To us, it seems but a formality for the
introduction to this country.
A
possible price increase of about two per cent will be a small
price to pay for anyone who wants the prestige provided by
Mercedes' latest technology aimed at making the planet a better
place for all of us.
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Marque Publishing Company
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