You know.....as I sit here thinking about the entire incident, this thought struck me. That rotary gear selector could be considered a dangerous mechanism. It slides too easily between gears and too quickly. A stick or shaft shifter is a little stiffer and slower but more positive in it's intentional position. Maybe the rotary selector is too gimmicky.

It certainly seems like you have some kind of malfunction in the electronic throttle control, but I don't agree at all that the rotary knob has anything to do with this conversation. I actually have come to find it quite intuitive, and there have been other kinds of shifters I've experienced that have had less "positive" detents or less intuitive operation.

Shifting into neutral will immediately halt any acceleration, regardless of throttle, and the brakes on any XF are more than capable of overcoming the torque generated by the engine.

Which model year do you own? From your description it sounds as if the transmission is in neutral when the engine rpm surges. There is software that opens the electronic throttle to maintain idle rpm when different loads are placed on the engine. Selecting D is one of those inputs. There are others such as alternator load and AC compressor load.

Jagular.......it is a late mfg. model for 2009 XF-SC

Ah, the XF-SC has a known vacuum leak problem underneath the supercharger. A rubber or foam gasket begins to leak, should throw a cel code though. Unless yours was fixed under warranty it may be the fault. Expensive to fix because the supercharger has to come out.

As for the rotary knob bear in mind that all modern automatics respond to a glorified electric switch. Whether the switch is a stick, rotary disk or push buttons makes no difference. What may be the trouble is some deficiency in the contacts of the switch. When the transmission selector repair was done on your car did you get the updated knob which has more cross hatching on the cylinder portion you grip? There were two recalls, one for the circuit board only and the second for replacement of the entire assembly, dial and all. I preferred the smoother feel of the older dial but the replacement worked correctly.

I had the same problem and yes it is the brake pedal depressed which goes lower than the accelerator and the harder you press brake the more the engine revs.It happened several times and now I position my foot differently to make sure the angle of the foot petal is such that it cannot touch the accelerator. Hasn't happened since

Scary stuff and glad no one has been hurt or property damaged as a result. Please keep us posted and hope your family is ok Chuck

A suggestion: Try left-foot braking. Takes some practice to learn it but, it is safer (quicker foot response) and much more performance oriented. Nearly all better race car drivers use left foot braking even in clutch type cars.

Albert

Whether you can safely learn to left foot brake depends a bit on your age. Also, not recommended if you also drive a three pedal car. I still occasionally left foot brake the XF thinking I'm pushing a non existent clutch and occasionally forget to push the clutch in the three pedal car when trying to start it. Fortunately my BRZ also has an ignition relay override switch on the clutch pedal. The SAAB Aero and the Alfa both still require that I focus on which car I'm in before I turn the key, but at least they have keys to differentiate them from my XF.

I don't do left foot braking as I have always been told it is not safe to do so. That was in my driver safety class in school too. If in a panic situation you will tend to press both feet down. Also tends to wear the brakes down if you rest your foot on the pedal. Mostly I know when someone is left foot braking is when you see the car in front of you with the brakes lights on or flickering.

Exactly Lew..it's just totally unsafe

OK.....NO left foot braking. But I have been thinking about what I wear on my feet. Most of the time I wear ECCO sandals (here in So. Calif.) and they could be a tad loose that might explain an accidental tap of the gas pedal just as I am applying the brake pedal since the brake pedal does go lower than the gas pedal when depressed. It is difficult to be aware of every movement of one's body parts when you are not really thinking about it.

I am sure it's an issue with lots of people, especially ones with big feet..(Like my size 12M)..I try to make a conscious effort to hit the brake pedal square in the middle, also it helps to prevent the classic pedal pad wear too.
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Looks like my manual shift brake pedal. I heel and toe all the time. Not so good with an automatic!

engine surge car in neutral and park
 

Wow, This strange thing just happened to me. My foot was on the brake as I was in traffic. Took foot off and car went forward too fast. Braked again. Same thing. Car was moving way too fast, NOT rolling. It was scary. I then put the car in neutral and it revved loudly. Back to drive and it went forward. My foot was NOT on the gas. I pulled off the road. Neutral LOUD rev. Put in Park - worse. Frantically hit the Stop /turn off button. Pshew. Nothing was under my gas pedal. My rug was not on the gas pedal. This was not driver error. I started the car and drove home fine. I will read more posts on this but..what the heck..

I always wonder why the way to turn off a car with a start/stop is to depress it for several seconds. In a panic you hit that puppy like a machine gun. That should be the signal "STOP THIS MOTHERFVCKER!!!) not a patient lalalala let's wait for the engine to stop, hold while pressing....