[DavyNM]

I've always gotten premium gas at my local Sam's Club. It's always 40 to 70 cents cheaper than premium gas at any other gas station in town. On top of that, it's only a miles from my house, so it's convenient. Never had an issue over the last 10 to 15 years on my other cars, including Acura, Mercedes, Lexus and Audi.

However, ever since I got my X1(U11) and M340i within the last couple of years, I've noticed that the cars felt somewhat "sluggish" if I top them up with premium gas at this Sam's Club. Just to make sure that it wasn't my imagination, I sometimes waited until the gas tanks werelow(the yellow light coming on) and topped off at the Shell station a few miles away. After driving for a while, I could definitely feel a difference. Also tried this with premium gas from Costco a couple of times.(but Costco is not in my town, so I only do it when I drive to another town)

Meanwhile, I still have two other cars in my family, the Acura and the Mercedes. Those two have around 42k miles and 50k miles, respectively. Still feel no difference in those two cars when I top them up with Sam's Club premium gas.

So, here are my questions:

(1) are BMW cars and SUVs just more sensitive to quality of gasoline?

or

(2) does my Sam's Club have "bad" or substandard premium gas? There seem to be quite a few Porsche owners who get gas there all the time(probably due to the fact there are a Porsche dealer and a Mercedes dealer just across the street). I talked to a couple of them and they said it was just my imagination.

(3) am I doing any long term damage by continuing to get gas at Sam's Club? Both my X1 and M340 are still quite new with less than 10k miles and they are purchased, not leased, because I usually keep my cars for a long time.

[RockCrusher]

Sam's Club 91 gasoline is probably not bad gasoline but gasoline quality can vary.

A UK gasoline test found Shell gasoline the best. Supermarket (discount) gasoline was almost as good but not always. Not consistently.

This variability was attributed to the allowable variation in the quality of the gasoline blend or to stale gasoline. Staleness could also affect Shell and other brands of gasoline. The takeaway was to shop/buy gasoline -- whatever the brand -- from a busy station to ensure fresh gasoline.

Sluggish performance suggests less than ideal combustion which could lead to an increase in engine deposits possibly degradation of the O2 sensors even the converters.

If some of your vehicles are consistently sluggish burning Sam's Club gasoline probably a sign you need to avoid that gasoline, at least for those vehicles which react unfavorably to it.

I mean it is a common recommendation in the owners manual that if the engine reacts unfavorably to a specific brand of gasoline to change brands of gasoline.

I'll add I have about 2 years or so back I switched to fueling my vehicles with Walmart 91E10. (Which could be the same gasoline sold by Sam's Club.)

None of my cars have exhibited any signs of any issues with Walmart 91E10 gasoline. (I had the opportunity to at a different gasoline station with 91 ethanol free gasoline and the various engines didn't react good or bad to the change.)

Also, when I fueled with some other brand of gasoline, to name a few: Philips 66, Unocal 76, Chevron, Shell; none of the engines perked up (or reacted unfavorably) to the change in brands.

As long as the engines in my cars/vehicles: currently a 2024 M8 and a 2024 Ridgeline; don't show any signs of issues with Walmart gasoline I'll continue to use it.

[spazzyfry123]

I can't directly speak to what you are experiencing - a lot of potential variables to cause that.

But with what seems like pretty consistent poor results, with dealerships and wholesale consumer outfits like Sam's in place, I'd say drive a mile down the road and find what's probably a dozen different fuel stations.