BMW developing stop-start technology for six-cylinder engines

[Bartek S.]

BMW currently offers autonomous engine stop-start technology for its four-cylinder engines under the guise of its EfficientDynamics ecological banner, but the fuel-saving feature is now expected to filter across to the carmaker’s award winning range of six-cylinder engines as well. The decision comes as BMW experiences falling sales of its larger powerplants, especially in Europe, and the first six-cylinder models with stop-start should be hitting showrooms within the next 12 months.

Stop-start systems essentially shut down an engine to save fuel when a car is sitting in idle traffic, and then almost instantly kick it back into life once the accelerator is depressed or the clutch is engaged. By doing this, stop-start systems offer the greatest fuel savings around town, where high cycle stop-and-go driving is common. The savings can be substantial, with four-cylinder models regularly returning savings of around 4-6% in fuel consumption. The fuel savings are expected to be higher in the six-cylinder models.

 

[GCfan]

I've driven both 118d pre and post facelift, the latter having the efficient dynamics package, for several thousands of kilometers. On the highway the fuel consumption is about 5% less with ED, while during city driving the consumption has decreased 10-15% on average (using the start-stop function, which you can switch off).

 

[chonkoa]

I think they need to do something for the V8 as well while they are at it.
They also need a way to shut off 50% of the cylinders under no-load conditions.
I think the biggest savings will be with the 6+ cylinder engines.

 

[EnI]

I think they need to do something for the V8 as well while they are at it.
They also need a way to shut off 50% of the cylinders under no-load conditions.

V8 models will get additional ED features soon.

Eg. automatic-stop-start function will debut with new super-efficient 8-speed automatic gearbox.


Also the V8 engines will be paired with electro-motor:

2 ActiveHybrids:

full hybrid (with two-mode active transmission)
&
mild hybrid (electro-motor built in a gearbox - to produce torque boost when accelerating).

 

[Bartek S.]

In September, we talked intensively about BMW’s new Start/Stop System as being part of the “EfficientDynamics” program. The stop-start system is one of the fuel economy and emissions reduction components of its “Efficient Dynamics” technology package. The way it works is that the system automatically switches off the engine when the car comes to a standstill. As soon as the driver puts in the clutch or depresses the gas pedal, the engine fires up automatically.
At that time, we confirmed the Start/Stop system only works for manual transmissions, but we had hopes that a solution for the automatic gearboxes will be developed as well. Three months later and the latest news say BMW’s new ZF eight-speed automatic gearbox will feature the Start/Stop technology also.
It is unknown at the moment which models will be getting this system, but my best goes on the high-end 760Li which will be released by the end of 2009.

Source: BMWToday