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BMW 328i: Regular or Premium Fuel?

So, my son bought the 2000 BMW 328i- I am keeping it for him until he deals with the speeding tickets… anyway… I filled the tank with regular gas- according to the owner’s manual, premium is recommended, but the motor will run on regular fuel, albeit with less horsepower and worse fuel economy. Should I keep running it on regular? Or put in premium at the next fill-up? My buddy, Larry the BMW Lover, said “You won’t notice the power difference or mileage difference-- so save money, and use regular gas.” What do you think? Regular? Or premium?

according to the owner’s manual, premium is recommended,

Recommended means just that.   [b] No damage will result using regular.[/b]  You will get some reduction in power and mileage.  You also will likely save a little in fuel cost as well.   Considering your son's history, I would suggest regular, it might slow him down just a little. ?

With the increase of fuel prices premium still remains $0.20 - $0.25 more than regular. Interestingly at $2.00/gallon the same was true.

So currently its about 5% more for premium fuel than regular. Check your MPG closely as it may drop that much. Mine definitely does drop that much in my premium required car and the power loss in noticable. However the motor (Subaru WRX) is more a sling shot powerband than a flatter one like a BMW.

Check your MPG over a full tank with regular.

Andrew_j worded it well.

If your BMW currently averages 20mpg, and a switch to regular drops the mileage by more than 1mpg, then using regular is costing you more money!

Is that what you want?

Is it possible the access your mileage down to that amount of deviation? I mean if you could even tell you were off by 1 mpg would it be possible that there was another reason (besides the fuel type) that cost you 1 mpg? I don’t feel that this car or customer is capable of determining their mileage with such accuracy, I am sure many feel they can though.

If a customer came in and complained of his mileage being off by 1 mpg I would be looking for the “tin foil hat” to send him home with (he could keep the hat).My first question would be “how could you possibly measure this small amount of change”?

I think the point is that he’s probably not saving money by using regular anyway.

Personally, I think his son should be part of the decision. And, under the circumstances, his son should be paying for the gas.

There might be a small savings overall IF the OP doesn’t do rabbit starts and keeps the speed down. But then why own a BMW…

It probably depends a lot on your driving conditions.

The only sure way to see if regular is thriftier for YOU is to just do it.

He doesn’t. He’s driving it for his son until his son “deals with the speeding tickets”. That’s why I think the son should decide what grade gas he wants in the tank and should be paying for it.

Premium car.
premium fuel.

don’t like it?
don’t drive it.

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From the owner’s manual

Fuel specifications
The engine uses lead-free gasoline
Required fuel:

Premium Unleaded Gasoline,
min. 91 AKI.
AKI = Anti Knock Index

So yeah, premium car, premium fuel.

I too thought premium was required. The owners manuals from the 2004-5 timeframe do require it. However, when I found this BMW owners manual for a 2000 328i, it only says “recommended”.

The manual is at:
The relevant text is:

Use unleaded gasoline only.

Recommended fuel: Premium with a minimum octane rating of 91 AKI.

BMW engines are equipped with knock sensors and will adapt automatically to
different octane ratings, provided that the minimum octane requirement
(87 AKI) is met.

Fuels with higher octane ratings will provide enhanced performance and lower
fuel consumption, while the use of fuels with lower octane ratings will have the
opposite effect.

That last paragraph does imply that engine will run in a “detuned” mode on regular - leading to decreased mpg.

Thanks to everyone… my mechanic said, “It’s an expensive car, so don’t scrimp on the gas”… actually, it’s not the cost of the gas, really… I was just curious if using regular made any difference… I am doing a mileage test right now (down to half a tank). My son is a college student, and works part-time, so, no, he doesn’t pay all of his costs: I pay for his gas. Me? I drive a truck, cos I hate the “rich-snob-SOB” image of Beemers (even tho he bought this one used for $7,000-- less than a new Kia). Of course, the REAL cost of a BMW isn’t the gas or the purchase price, but the exorbitant cost of repairs!!!