BMW slashes emissions in new six-cylinder petrol

MUNICH: The days of the combustion engine may be numbered, but that has not stopped engineers at BMW from coaxing more economy from the marque's signature engine.

Fuel consumption of the next generation of inline six-cylinder engines, which will power the 7 Series luxury limousine and the X7 SUV from BMW, is said to be within striking distance of the traditionally frugal diesel.

The new engine consumes one litre less of fuel per 100km than its predecessor, thanks to some clever tuning, the German manufacturer told the Frankfurter Allgemeine Zeitung newspaper.

BMW has invested heavily in the new technology despite an effective European Union ban for new fossil-fuel cars from 2035.

This move aims to accelerate the switch to zero-emission electric vehicles as part of a broad package of measures to reduce BMW's contribution to climate change.

"We have everything in it that money can buy," BMW engine chief Roland Welzmüller told the newspaper.

The reduced consumption is mainly due to the combination of two technology modules. The first element reduces drag losses that occur when the driver takes their foot off the accelerator.

The variable valve duration system also means the engine valves close for longer, allowing the pistons to press against the fuel mixture in the cylinders for a fraction of a second longer before it is burned and the exhaust gases released.

The resulting kick-back energy drives a generator connected to the crankshaft, which turns out to 17 kWh of power at the low engine speeds when consumption is normally high.

In addition at faster speeds, only as much fuel enters the engine as actually needs to be burned.

The engine is fit for more stringent Euro7 exhaust emission laws due to be released in future and the unit slashes particle emissions by up to 95%.

Overall, the engine's raw emissions are said to be reduced by half. The rest is taken care of by the exhaust system, which has also been revised and combines a new three-way catalytic converter with a finer particle filter.

A second catalytic converter in the underbody, which has long been standard for BMW in Europe, enhances the cleaning effect. Welzmüller is confident that the engine is suitable for the upcoming emissions standard without major modifications.