same here and I also have been running regular gas for the past 20 years of owning my E53 with no issues

Not sure how you pulled that off. When I ran out of gas and sister in law brought me 87, check engine 3x in the 5 mile drive to the nearest station.


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I also use regular gas almost all year. The only time I put premium in is when I am towing the trailer and sometimes one tank immediately before I know I'll be towing. Never had a problem, can't even tell the difference.

Which motor? I suspect the v8s can cope better. I noticed the difference immediately when I even used mid grade but that could be due to crap formulated gas with ethanol.

I'm using 89 no ethanol currently and no difference from 93 with ethanol. (N55 motor)


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Premium only here. But in Texas currently it's only ~$3/gallon. What really hurt was when gas hit $5+ ($100+/tank) back in 2019 I think it was... maybe '18. Would have to check my records.

For what it's worth, which is nothing obviously, I'd never put less than premium in. Knock is not something I want to chance over 10:1 compression. Besides, around here you'd save maybe $15 a tank. We're not wealthy, far from it... but an extra $75/mo for the 5 fillups isn't going to break us either.

I've run nothing but regular in my M52TU, M54, and N52. Never an issue. I live at altitude, so regular is actually 85 octane here. I've filled up and headed east to lower elevation and still not encountered any problems. If I think about it before heading to lower elevation, I'll maybe feel guilty and put at least midgrade in, but I won't go out of my way to do it. As someone mentioned, I DID buy midgrade or premium when I used to tow with my E53/M54. I was working it pretty hard with my camper - which is why I now have an E70/35D.

AM.

I don't think that was the low octane. I'd guess maybe that gas can had some crap in it or something.

AM.

For the last 2 years, been running regular...wish I had at the start of ownership. No problems what so ever. But it may have benefitted the M54 X3 06 seeing that I ran top tier premium all those years in the past. However, the noticeable difference (to me) is hwy milage.
In the city... about 19.9.....
On the hwy using Cruz control at say the sweet spot 70mph....gives me 26 mpg. And that's with recent proper oil change, new plugs, tires correctly inflated, me cleaning the icv,MAF, throttle body,air filter and me not carrying a bunch of crap in the back boot.

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I have always used the highest octane available at the station. It amazes and also saddens me that these cars are now at the price point where the owners go as far as cheaping out on the fuel let alone the vast amount of maintenance and repairs their X5's most likely need. If you go as far as trying to save literal pennies on gas, you should buy a different car.

@crystalworks just said he spends $75/mo to use premium instead of regular.... to me, that's just flushing money down the toilet using premium to drive your family to Starbucks when regular does just fine.



I paid $6,300 for this car 7.5 years ago, so at $75/mo., I would have saved more than enough money to buy another one just like it by now, or I could just use regular which has worked fine for me for the past 7.5 years. Like you see in this thread, the sky does not immediately fall if our fancy special krautwagens sip a drop of regular. Many of us in this thread have proved that by experience. You know what happens when you fill up with regular? The DME pulls a bit of timing... it doesn't know the difference and just uses the knock sensor to take care of itself.