HyperS4

Its also recommended that you eat nutritional food to maintain full energy and keep all moving parts working at its peak. Can you eat McDonalds, sure, but would you want to eat it every day and try to run off it? McDonalds is 87 Octane...think about it.

VM

I think that's a bad analogy because human nutrition is complicated in a way that... engine fuel selection is not.

Fundamentally, 87 octane and 91 octane are not lower quality vs higher quality (ignoring fuel companies' practice of adding additional additives to 91). They are two different chemical mixtures with different properties, especially relating to pre-detonation. Engines, especially modern ones, are carefully engineered around the chemical properties of one fuel or another, then additional systems are engineered to accomodate fuel with less than those properties.

I would never feel bad about, say, putting 87 in a GM 3.8L V6 (or, for that matter, a Hyundai Lambda V6). That's what it's designed for! But the A4, like the overwhelming majority of European cars, has an engine engineered around 95 RON, aka 91 AKI.

Bestcar17

If McDonalds is 87 then Wendy's has to be 93, their milkshake do taste better.

HyperS4

You hit the nail on the head. The cars that are "designed" for regular gas are not high compression or even commonly turbocharged, they are NA engines. Which completely defines the reason why the Audi(and BMW, Mercedes etc.) basically require OVER 91 octane to function to their fullest. Just because a car has programming and anti-knock sensors blah blah to protect in the situation you are running lower octane, why would you want to abuse your engine? I never understood why this debate even comes up on forums for cars that are 50k plus. Unless you are in the middle of hills that have eyes and only 87 gas is available, use the correct gas.

raaizin

I had a 2007 Audi A6 3.2 which had 12.5:1 compression by the way which had same writing in owners manual. I put regular in it for 150,000 miles with no ill effects. The engine was in perfect running order. I would not hesitate to use regular and I do in my 2018 A4 and wifes 2018 Q5. As for the original poster $500 a year take it 10 years out that is 5k, not an insignificant account. Sure you will lose a few HP but you will not notice it .

HyperS4

Try telling that to people who actually enjoy driving their cars...

Q5 Bob

A couple of manufacturers (Mazda) comes to mind) list the hp/tq ratings on both regular and premium. Makes it easier for the driver to determine what they want to put in the tank. In Mazda's case their 2.5 turbo engine makes 227hp on regular and 250hp on premium fuel. Torque remains the same @ 310 lb. ft. with either grade of fuel.

volcomic

... That's $150K+ in car MSRP and you're worried about $5K over 10 years!?

Bestcar17

Guarantee if one skimp on gas they would skimp on maintenance too. 150k on 87 sounds sketchy for an Audi

chych

Seriously... if regular vs. premium was a factor, one should question whether they should be getting an Audi instead of a $20k Toyota instead.