Start stop function

The new 991 has start/stop as does the Panamera I've read. This sounds weird in a high performance sports car. Anyone have experience or comments on this "feature"? Reminds me of the Corvette tranny that shifted from 2nd to 4th regardless of the driver's desire.

I rented a 2011 MB SLK that had this feature this summer during a weekend visiting friends in Monte Carlo . Really, really annoying! We had the top down and were trying to follow the navigation system to our friend's place so we did not notice it was the engine shutting off, rather what I noticed was a long hesitation when I wanted to accelerate from a stop. This of course was the lag caused by the engine shutting off and restarting when I pressed the accelerator. Shifting to Sport Mode was the only way to not have it intervene.

My wife has a 2011 Cayenne that has the start stop function with the 8 speed Tiptronic S transmission. The purpose of the feature is to save gas when in traffic or at a light. The engine turns off when you hold the brake petal down and restarts when you release the pedal. We never use the feature and always have it turned off. The starter is more robust and built to handle the feature. I would think that this is another way Porsche is trying to reduce fuel usage and make the car more environmentally friendly. Like keyless entry/keyless start Porsche is using it to draw BMW and Mercedez owners. These are creature comfort features that are in sport coupes/sport sedans which are not supposed to be in real sport cars. If you look at the new Porsche lineup: Cayenne, Panamera, 991 and most likely 981 that all share the same features. Looks like Porsche is usingg the same features for every line to save money.

We have it on our Cayenne also - I find it to be a minor annoyance in stop and go driving (with very shorts stops) - it is rather jerky when it restarts. Our RX400h was much smoother in this regard, though it did have the electric motor to get you started. I'm not sure how it would work with a manual tranny and clutch. I do switch it on when I'm driving a route where I know I will be waiting at long stop lights. At least Porsche gave us the option to switch it on and off as you like.

I guess if you can turn it off, it's not a big deal. Hopefully that's the way the 991 will be.

I agree...I have had my Cayenne for only 300 miles, and sometimes I like it, but other times it is annoying...you are just too aware of it happening to have it be turned on in bumper to bumper traffic that moves from stop to slow often. I have just turned it off...

Definitely a not so good choice on Porsche for the 991. They shouldn't put this stuff in high end sports cars. Even in a Cayenne or a Panamera. I couldn't imagine being in a Cayenne going up a rocky hill offloading and then the engine shuts off.

Actually, the Stop-Start function is disabled when the off-road program is active in the Cayenne.

The corvette shift from 2nd to 4th was a feature only on the manual transmissions, and you could defeat the feature if desired....

I have had both a CayenneS and a Panamera 4S "loaner" with this "feature" for long weekends that included driving from Atlanta to the North Georgia mountains for some PCA functions. In both cases, my wife was driving them most of the time while I drove my CaymanS . With the Cayenne, I played with it and found it very annoying, and before I gave her the keys, I disabled it. With the Panamera, I forgot to disable it, and forgot to tell her about it. A little while into the trip, she started freaking out that something was wrong, and quickly called me. I just chuckled and told her what it was, and how to turn it off. In any case, maybe it is something you can get used to, and it is certainly a gimmick to help save a milliliter of gas every 100 miles in "real driving" but in thier mileage certification it must help out signifincantly enough to help with the mileage ratings..........

I test drove a car with it... hated it. A complete waste of r&d and extra cost to the car if you asked me.

I was wondering about this as well. It could be useful in really bad traffic. But in daily driving, probably not. I know the 981 Boxsters have this feature. With a manual, the system will shut off the engine when you depress the clutch, shift into neutral and release the clutch. Depressing the clutch again, and shifting into 1st restarts the engine. Auto Start/Stop is certainly being used in Europe to help reduce emissions and improve fuel economy on many vehicles. Once my car arrives, I'll test it out and see what I think.

Guys, you can shut off the Auto On/Off feature on the 991 and I do. Hate it.

Also, if you do leave it on, it won't work unless favorable conditions are present. For example in hot weather with the AC and radio on it the engine usually doesn't stop. I keep mine set to not work but try it occasionally to see if I can stand it. I always confirm that I can't. On the highway however, if there is lot of traffic, I set it to work as that also enables "sailing" by which the engine idles when it can, totally seamlessly. Besides breaking up to boredom of traffic, it gets unexpectedly good MPG if cruising gently in 7th (not a penalty as 2200 rpm = 80 mph). In the Nav, there is a "car" screen setting that shows ave speeds and MPG, and watching the MPG creep up mildly interesting. I recently got 29 MPG on a long trip largely by focusing on moving up by tenths, and found myself home about 40 minutes faster than usual so as to ruin it by stopping. Very hard on the bladder. PS engine stopped on hills is no issue on hills as there is "hill hold" standard.

So my question is do you have to disable this every time you get in the car, or can you configure it to default to off. If you have to disable it every time I will probably spend some time with a tech and pwis to see if we can change the default.

I have it on my 981 S and when you disable it it will stay disabled until you change it so it's not bad. I tried to leave the auto start on but I can't stand it, especially in a 6-SP M/T.

I can see start/stop in a hybrid, where you have an electric motor to get you going until the engine kicks in. But without an electric motor? I'm not sure that works, especially in a sports car. Isn't there a bit of a delay when the engine starts?

I can speak from M/T point of view. When you're at a stop, on the brake, in neutral with clutch out the engine stops. As soon as you depress the clutch the engine starts. It doesn't introduce any additional delay for M/T but is nerve wracking not having your engine running through.

For normal driving as soon as the clutch is fully depressed and before you completed shift into gear the engine is stabled at normal idle speed. If you are fast I think you can beat the system but you have to try very hard.

Cool, thanks. Still, start/stop in a non-hybrid, especially a M/T, seems strange to me.

Remember this feature helps porsche get their overall fleet mpg avg up. If it increases mpg in each vehicle by 2 mpg, that really looks good on paper overall. I dont think porsche cares if you use it, or there would not be a way to disable...

Start stop also required the new steering system I believe.

Good point... Next time I need to test to see if the power steering is assisted when the engine is off by the start/stop feature. If it works then it would explain the electric power steering.

While my early build 991 is in the shop for the factory campaign to correct front compartment weather sealing, I have a Panamera (V6) as a loaner. In the 991 I find the start-stop "feature" intrusive and keep it disabled. Just the opposite with the Panamera. It is not a bother at all, so I leave it on. I think it is because engine in the Panamera is so much more isolated in terms of noise and vibration. It disables itself in Sport mode and when the AC is on in any case.