When I was out early today driving on smooth blacktop, light drizzle rain. At about 40 mph under acceleration, I noticed a slight vibration feel and I could just detect it feeling the steering wheel. It doesn’t last long, maybe 30 seconds? Not while coasting, not at higher speeds. I just noticed it when I turned the radio off. It saddens me that this will make me return this car I really want to keep. The dealer can’t check the car in time to make it under the 10 day return. The car is still 3/4 full of gas from the dealer - it could be old gas but it doesn’t make sense that bad gas could be the cause.
This is barely noticeable but just the same it’s there and I’m afraid it could get worse. I’m really upset with myself that l just noticed this after all I went through this week.
I would really appreciate any Ideas to find out more and a possible reason.

Thanks for your time in advance!
Rich

Bent wheel, out of balance tire, hard to say....

Actually, it could be bad gas. No way to know for sure, but if there are impurities, especially water, you might only notice it at a certain rpm and load range. I once had bad gas and my car rumbled terribly, it almost felt like mini rumble strips. Worst part is I was in the middle of Idaho, heading to Montana. The car made the trip just fine. And after filling up the sound/feeling went away and never returned.

Every single one of your posts tells me that you are looking for a reason to return the car instead of looking for one to keep it ! Buyers remorse maybe . Your heart isn’t in it , do it so you can relax and get back in it at a later time .

Cylinder deactivation?

IMO it seems pretty clear you are looking for reasons to return the car. I would return the car and get something that you're comfortable with.

Take a good look at the tires and wheels.
Could be a missing balance weight.
Missing stem cap.
The tire might have an embedded metal object.
It could be an under inflated tire.
Possibly a loose wheel bearing.
Anything that rotates, and is out of balance, can cause a vibration.

Actually I really like this car, it’s a great color, the interior looks great, It has all the options I like, I rather have lower miles, and a year or two newer ( maybe a bit cheaper) but I have exceeded 40 hrs over 60 days and I concluded a fully loaded S560 4matic in a color other than Black with something other than a monotone interior isn’t appearing anytime soon.
My habit of giving up and moving on towards a different car could very well happen, and I may come back to an S class hunt next year or later or not.

A situation exists in real estate that could resemble this. A realtor shows a couple a house that they fall in love with. This couple vacillates and looses the opportunity they were seeking. From there after any other house they see never measures up to the one that got away. Understand?

I just wanted to get my feet wet. Sure, an AMG S63 would be an easier hunt, I could be very happy finding one with all the better, most popular options like 3D sound, W&C, Premium package, Driver’s assist and a half dozen others - original msrp sticker at around $170,000 but it would run 80% more. I’m not ready for that much yet

I'm a real estate agent, and this does happen but you understand that the couple in question has hurt themselves, right? You need to have confidence in your choices and be ready to make a big commitment before you jump in and make it. My guess is you thought of this scenario because you have done this with a home search too, am I right? I'll let a buyer do that one time...but if they do it a second time then they're fired lol

I know you like and want the car, but you're letting your own overthinking and worry keep you from taking the leap. Looking for something and investing the time and energy into shopping for it takes up your time and energy as well as the time and energy of others. It takes up our time and energy even trying to advise you and help you by answering your posts. Dealers who show you cars and sell you cars only to have you return them...if you're not ready you should wait until you are ready.

You realize this is illogical right? You want a car a year or two newer with lower miles but you also want it cheaper? You want "better, but for less" that doesn't exist.

There is a known issue that if the eco button remains on it can cause a slight vibration at various speeds ranging from 5mph to 75mph; I had this issue a couple of years ago. Turning the eco button off eliminated the vibration issue for me (and several others here).

UPDATE*

Last night I called the dealer to ask where they were in their repairs process. They found the cause of the vibration, a flat spot on the right front tire.

Now a different part of the story.
When I put this car on the lift I noticed the tires, they were pretty well worn. In fact I measured between 3/32” to just barely under 4/32.” I remembered when I informed CarMax I might get an independent inspection done the salesman said “There’s no reason to need any other inspections, CarMax does a 160 point inspection and they fixe anything needed. On Tuesday I had an appointment for CarMax to look over my claims. They agreed there was a vibration and when it came to looking at the tires the service manager checked each tire about a half dozen times, then he repeated going around to each tire measuring again. He reluctantly said with his head down and avoiding eye contact that he got 4/32” - their threshold for being good enough to pass. I told him he could start writing my refund check, I’m returning this car. “Let me partner up with my manager and discuss this.”
A woman (who I could swear I know her as just another salesman) comes over for her confirmation. She did each tire just like the other guy and after then told me they will replace the tires.
I asked if I could make a request. Continental Procontacts are on this car, I have a better tire that will cost nearly half - the Continental ExtremeContact DWS 06 Plus. They agreed they will give me those tires.
When I picked up the car last night I found the new tires were the same tires they just replaced. I told them this is unacceptable and this is my 10th day to invoke the return policy. This was over heard by their new general manager just brought in to improve this store’s short comings. He tried to get me to accept the tires, but I dug my heals in and said no way. By the end of the night he offered to spare me more hours spent traveling back and forth and will let do everything myself and he would reimburse me the costs.

I’m working on getting this in writing and then call TireRack for the tires in a few minutes.

Rich

New tires coming tomorrow, that’s fast! There is a local mobile tire service, I hope they can do the same balance the shop can do.

You're going to want a road force balance...

Turn off the auto stop start. That also deactivates the cylinder shut down.

Bet $5 it goes away.

Pressing that button is muscle memory after starting it up. And I still get 29mpg on the highway.

They found that he had a flat spotted tire. He's getting new tires I told him he should ask for a road force balance.

ONLY road force balance, it is night and day versus regular balance !

Totally, I only have wheels road force balanced