Mercedes backs combustion
08 August 2007
Diesel and petrol will still be key in the future - that's why Mercedes' investing in both. Paul Barker reports
The death of the combustion engine has been greatly exaggerated. That was the message from an exclusive technology day BusinessCar was invited to at Mercedes' famous museum in Stuttgart last month.
Ambitious plans see the German prestige brand aim to push the development of engines until diesels are as clean as petrols, and petrols offer the same economy as diesels. And both have to be without any loss of power or performance.
Though fuel cell vehicles are presumed to be the long-term future, Mercedes thinks that combustion engines will remain a big part of transport - even after fuel cell introduction. The company also feels diesel technological improvements can do more to reduce CO2 emissions than hybrids (see 'Why not hybrid?' below). "As a result we decided to intensely address the only weakness of diesel, namely its emissions," said the head of Mercedes diesel engine development Dr Joachim Schommers. The firm spends 5.6bn Euros (£3.8bn) a year in research and development, and a major focus is currently fuel efficiency and emissions.
Mercedes claims the Bluetec technology in its engine, which is already launched in the diesel-sceptic United States and is described by the company as the world's cleanest unit, achieves its goal of cutting diesel emissions to petrol levels. It's headed for Europe, if not yet England for at this stage.
But the bigger long-term development comes in the second part of Mercedes-Benz's goal, namely a petrol engine with the economy of a diesel. Petrol engines "will remain attractive in many markets and for many customers," said Mercedes' powertrain vice-president Prof Herbert Kohler, justifying the company's decision to push forward with its new advances.
Mercedes engineers claim to have scored something of a first by developing a petrol engine with the pulling power and fuel consumption of a diesel. Branded DiesOtto, the system won't be a production reality until sometime around 2012-2015, but the German brand claims a 1.8-litre turbocharged DiesOtto engine can offer 238PS, around the same as its current 3.5-litre V6 petrol unit. Achieved via a number of innovations such as a diesel-like combustion process called Controlled Auto Ignition, it will be premiered in an S-class-sized concept car at September's Frankfurt motor show, complete with claimed economy figures of 42.0mpg.
The Diesotto engine will also be mated to a hybrid powertrain to boost urban fuel consumption when it makes production, though that's still some way off as lab tests have only just been completed. "We have an engine in the laboratory that proves it can be put into production," said Prof Kohler, who also confirmed that the unit runs on conventional unleaded, not special low-sulphur or super unleaded fuels.
"With Bluetec on one hand and Diesotto on the other, we have underlined one thing - the next generation of combustion engines will come," concluded Prof Kohler.