Strife1013

I think the only way to truly measure this would to be having two of the same car driving at the exact conditions, speeds, stops, length of time stopped at red lights, stop signs, same tires, tire air pressure, fuel, weather conditions, altitude, same mileage driven, etc... (basically impossible) to see how helpful having the start stop feature is in saving gas.

Than if all that was done in a lab does that match actual real life driving conditions?!?

For me it comes down to usefulness. During rush hour I turn it off because it's too much stop and go and I think I gain no real advantage having my car off of 3 seconds every 10 seconds. However during the weekend with lighter traffic and what not I will leave it on because I am at a standstill longer than rush hour traffic.

ryanwarner

The value of stop start is debatable, but I definitely think that unlocking the axels into free wheeling mode makes a difference. If I time it right and I'm heading down hill, I can cost for quite awhile.

VM

If you learn how to modulate the brake pedal, you can basically avoid it stopping while in stop-and-go traffic, while still having it stop when you are at an intersection where you know you won't move for a while...

-peterp-

you are killing the transmission doing this (manual or dsg, doesn't matter, source: ).
And to respond to the start/stop effectiveness, my B9 manual says if you are going to idle for 30-40 seconds, it's better to let the engine stop. Otherwise you are not saving and are actually stressing other components of the car and engine.

-peterp-

This statement is semi-correct. The bar has got everything to do with the fuel consumption.
The manual says

• Recuperation: Electrical energy can be stored in the battery (recuperation) if the vehicle is travelling downhill or coasting in gear (overrun). In this case, the bar will move towards the (battery) symbol.

And I am with OP that the consumption bar logic is silly - I was stopping at lights earlier today and seen avg fuel consumption jump from 8.0 to 10.5 l/100km (btw the units can be set in MMI, l/100km, km/l, mpg, maybe others I can't remember) in a few seconds. I believe in such situations and with start/stop disengaged (for whatever reasons), the computer should stop counting the time towards avg consumption. As you are really consuming much less (more like 1.5-2l/hr). Then again, it's average fuel/distance so when stopped, it skyrockets :-)

VM

Huh? Are you claiming that you need to push the brake down enough to trigger the start-stop system in order for the clutch to be released?

-peterp-

That is my understanding, yes. In reverse - when stopped in start/stop, just releasing the brake pedal from full push starts the engine.

VM

But... that would mean that you would NEVER disengage the clutch unless the engine was stopped. That can't be right - does Audi really intend for the engine to turn off and restart every time you stop at a stop sign for half a second?

-peterp-

From what I understood, the clutch is disengaged when: 1) you fully push brake pedal 2) the situation - your speed, throttle or braking and slope (if indicated so by the nav data) suggest no speed should be engaged (seen it a couple of time coasting downhill when E4 turned to just E or D5 turned to just D).
Hmm, to the last statement, here's what Audi actually says:

The new cruise control includes an impressive efficiency function: When the driver lifts his or her foot from the accelerator pedal in mode D or E, the transmission shifts to freewheeling whenever that would result in fuel savings. This coasting mode is possible between 55 and 160 km/h (34.2-99.4 mph). The function can anticipate even more effectively when a car has the optional systems predictive efficiency assist and Stop&Go adaptive cruise control including traffic-jam assist.

Oh - so I must've been in CC. That explains! =D

Nilesh Makan

It was never like this. My fuel consumption is sitting at 27 because is this. Please help.