At highway speeds, my 2016 S F56 has what I would describe as a periodic tremble or vibration in the steering wheel. Like every 2 seconds, comes and goes. Does this with A/C on or off, and is not road speed dependent It is subtle, but definitely there. Anyone else? Thoughts?

 

Any thing recently done to the car?

Is tire pressure ok? Cold weather will have tire inflation pressures way down. (I've also experienced tire vibration not unlike the tire being out of balance from too much tire pressure, too.)

Possibly alignment. If you bump into curbs when pulling into a parking space or cut too sharp a turn when turning into a drive and run a rear (or even a front) wheel/tire over the curb this can upset alignment. (In my Porsche Turbo I pulled too far into a hotel parking lot and both front tires just bumped into the sidewalk edge. Long story short this had the front tires howling to the point I though a wheel bearing was bad. But a tech checked the car over and noticed the tire tread blocks had signs of feathering and cupping which was due to alignment. Sure enough when I got home I had the car aligned -- front toe was out -- and afterwards after some few hundreds of miles to give the front tires time to "scrub" in the howl was gone.)

Tires can go out of balance. One can lose a tire weight or as the tires wear and as the heavy spots wear away the tire goes slightly out of balance. Wider tires are more prone to this but it can happen with any tire. A tire re balance will be needed. (With both my previous cars, a Boxster and a Porsche Turbo, often after 20K miles when the rear tires were worn out I'd have the front tires rebalanced to address tire imbalance due to wear at the same time I had new rear tires installed.)

If you live where there is snow/ice this can build up on the wheels and affect balance.

If the car is equipped with a hydraulic power steering system be sure the fluid level is good. If it is low there can be a leak and this has to be checked for.

 

 

Car has 22,000 miles and still on the original run flat tires. But, as I said, not speed dependent so perhaps something in the power steering electric motor? Of course it is 4 months out of warranty.