newmoon

I was browsing the Audi UK brochure for the A6 and I found this:

Recuperation
When a vehicle brakes, the discs convert
kinetic energy into thermal energy, which is wasted
as it cannot be used. With a recuperation system
like the one in the Audi A6, the kinetic energy is
converted into useful electrical energy. The way
it works is simple. While the car is coasting or
braking, the alternator voltage is raised above the
level of the basic electrical system, which enables
the alternator to generate electrical energy and
store it temporarily in the battery. When the vehicle
accelerates, this energy is used to relieve the load on
the alternator, resulting in a fuel saving of up to 3%.

Which does sound like it follows a hybrid car's principles of storing kinetic energy as electrical energy when you brake, and using it when you accelerate, although in this case it is just used to relieve the load on the alternator and hence the engine, not drive the car.

So, if you were wondering what that battery icon was at the high end of the fuel economy display was, this is probably it.

AcuraUpToAudi

I was indeed wondering about that battery icon. Now it makes sense. Cool. Thanks.

MileHighJC

Maybe Im just having a dim day... how is that different than how the alternator works with the battery on any car? Is that not the purpose of the alternator?

Or pehaps is this marketing speak for "the car charges the battery when it is running."

dbg_dbg

Same. I wondered what that battery was for. Now I know. Thanks!

DeerHunter

The alternator required power (usually from the engine) to generate the power required by all the vehicle accessories and to charge the battery. Normally, this happens while the car is cruising and requires additional fuel to cover the extra load.

Audi, quite cleverly, charges the battery mainly on engine over-run (when the power required by the alternator is provided by the momentum of your car). It's not going to double your mileage, but it is an incremental improvement and it cost the manufacturer relatively little to implement.

irenesbob

In the 2013 A6 Order Guide "Start/Stop system with energy recovery" is listed as a standard feature for all levels of the 3.0 A6. Since the 2.0 models do not have S/S I am assuming they probably do not have "energy recovery."
It seems likely to me that Audi decided it would be better to have the energy recovery system to ensure that the frequent re-starts with the S/S system don't drain the battery, rather than install a very heavy battery. I am glad my 2.0 does not have either the S/S system or the "energy recovery" system.

DeerHunter

The 2.0T A6 loaner I recently had had the energy recovery system. There's no harm in having it (and some good), since it doesn't affect drivability like start/stop sometimes does.

snagitseven

The start/stop system is fully defeatable with a simple one-time push of a button. It's a non issue.