http://green.autoblog.com/2010/06/18/2011-...ke-energy-rege/

Apparently BMW has been doing this for a couple years, and it's new to Porsche. The engineering nerd in me likes it. I wonder why I haven't heard of it before? Maybe I just missed the discussion.

Anyway, it works by first equipping the car with a deep-cycle battery that doesn't mind being drained. Then during acceleration and some cruising, the alternator is disabled and the electrics run off battery only. Porsche says the MPG goes from 19.3 to 20.5 mpg. Finally, to recharge the battery, the alternator is only used during braking and lift-throttle operation.

(I'm sure for highway driving, once the battery capacity gets low enough, the alternator is used to keep things running.)

It's not a huge increase in mileage, but it seems to only require a new battery and a software change. It sounds like something that could very easily be adapted to every non-hybrid out there for minimal cost, and provide some decent savings. ($136 per year for the Panamera at 15k miles per year and $3/gal.)

 

My M3 has it, and BMW claims up to 3% energy savings. Net net, it turns a big gas hog into a slightly less big gas hog!

 

I assume the M3 requires a special battery?

 

I have no idea.

 

I'm assuming that the alternator just has some sort of a clutch on it, right? Why not do the same treatment to the power steering pump? You don't need that loss all of time either.


This is the part where you guys tell me that if I owned a car from this decade that I would already know that X car already does this, right?

 

What, like the S2000 not even having a power steering pump?

Anyway, sounds like there isn't clutch for the alternator, rather they simply run it with zero load - so it freewheels without resistance.

 

Now they just need to add cylinder deactivation, and auto stop like Honda.

 

Funny you say that: "The Auto Start Stop function has also been optimised, now allowing the driver to set off again even faster and more comfortably after coming to a halt."

I just didn't mention it, along with the low rolling resistance tires, because it's older tech.

(Far as I can tell, cylinder deactivation isn't part of the Porsche lineup anywhere.)