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10 | Setra Cover Story
Setra Cover Story | 11
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eginning in January 2014, the new Euro VI emission standard
will call for dramatically reduced emissions. The only
problem is that lowering harmful emissions almost automatically
increases fuel consumption and therefore costs. For the
new ComfortClass 500 with a Euro VI engine, the greatest challenge
was to reduce the emission of soot particles and nitrogen oxides,
while setting all-new standards in cost-effectiveness.
The ultimate consumption test
To achieve this ambitious goal, the ComfortClass 500’s new Blue-
Efficiency engine generation plays a key role – by uniquely combining
innovative technology and intelligent exhaust after-treatment.
Along with the use of cooled exhaust gas recirculation (EGR), the
engine relies on Mercedes-Benz’ BlueTec 6 technology, in which a
closed particulate filter and the successful SCR system complement
each other perfectly.
Other important measures in the vehicle’s development were the
lowering of air resistance by 20% and a significant reduction in
weight – which of course has an additional positive effect on fuel.
Internal Setra calculations indicated that the new Comfort-
Class 500 with Euro VI should consume 5—6% less fuel than its
predecessor, the ComfortClass 400 with Euro V. So far, all the
basic requirements for a fuel-efficient vehicle, right? But how
does the ComfortClass 500’s actual fuel consumption fare under
absolutely realistic conditions?
The Record Run Buses 2012 fuel comparison test from last October
was intended to provide irrefutable proof that fuel economy is possible
in spite of Euro VI. In this test drive, under everyday driving
conditions, the ComfortClass 500 with Euro VI and the Comfort-
Class 400 with Euro V were pitted against each other. And, to guarantee
that the results of the Record Run Buses 2012 would be 100
percent reliable, while delivering clear messages to Setra customers
regarding fuel consumption, the project responsibles at Setra looked
for a suitable partner. One that would embody technical expertise,
strict neutrality and unconditional diligence. DEKRA, the renowned
international testing, inspection and certification provider, fit the
bill perfectly.
DEKRA as neutral supervisory authority
DEKRA is one of the world’s leading expert organisations, active in
more than 50 countries. Close to 27,000 employees worldwide look
after the key areas of vehicle inspections, appraisals, industrial
testing services, product testing, certification and environmental
protection. DEKRA teams from several different locations took part
in the Record Run Buses 2012 event. The DEKRA Wiesbaden office
was involved in the early planning phase and contributed their expertise
to the professional preparation of the vehicles. To ensure the
most transparent, certified testing, the engineers sealed all components
essential for fuel consumption on both vehicles – including of
course, the fuel tanks themselves. “Only when any possibility of
manipulation is excluded a priori, can we assume that consumption
levels are absolutely binding and watertight,” explains Bernd
Pisecky, an engineer at the DEKRA office in Leipzig.
Identical starting conditions – to millimetre accuracy!
The DEKRA experts paid particular attention to having the two coaches
take to the starting block under identical competitive conditions. The
coaches were weighed – as in a boxing match. And both were fully
loaded to the allowable total vehicle weight of 18 tonnes. The S 515 HD,
with the new Mercedes-Benz OM 470 Euro VI engine, was pitted
against the previous comparable model, the ComfortClass 400
S 415 GT-HD with the previous OM 457 LA engine. Both vehicles
competed with exactly the same horsepower of 315 kW (428 hp). And,
finally, they were previously “broken in” with about 10,000 km.