MHSFBay

I wish someone from Shell or another Oil Company would set this all straight--

Jumping back to California-- I found that Union 76 sells 4-grades of high octane: 93/94/96/ 100. I usually use 94 (for price vs bang per buck-- It is currently over $5-- hell, most stations are over $4.15 out here for "Premium" 91, so 94 is a little expensive but hey, it is fun), and yes I get a little better "pull" with 94/ I tried 100, but in daily driving I couldn't sense difference.

djw07

My 2012 Q5 lists 91 Octane US as the appropriate fuel to use.

BayGBM

I drove my last car (a BMW 328ci) to 100k miles and never bought premium and it drove great. The car I had before that went more than 230k miles before I got rid of it and I never put premium in that either. I have a 2.0T Q5 now and I never buy premium. It drives great. If I were a racecar driver and needed to extract the absolute maximum performance out of my car I would indeed buy premium gasoline. I would also have premium racing tires on said vehicle. But that’s not the kind of driving I do; I drive to work, the gym, home, and other errands.

Over the years, some TV news magazines have done undercover investigations and every now and then they catch a gas station charging you for Premium when, in fact, they are selling you Regular. Imagine that! I guarantee that those of you who insist on buying Premium gasoline have been tricked into buying, and filling your tank with, Regular and you didn’t even know it.

Set your egos aside and answer this simple question. What seems more likely: there is really a dramatic difference between gasoline grades and we should all adhere those differences… or gasoline grades are a big scam concocted by the oil companies to separate you from even more of your money.

Consider this: we now live in a world where family SUVs and even the little Smart-for-2 car now claim that they require Premium fuel. And as small as it is the Smart does not even get good gas milage.... so what exactly are you paying Premium for?

DJRobNM

I drove an 2011 a4 2.0 TFSI from Detroit to St. Louis last year. On the way there with 93 octane I averaged 29mpg. One the way back I put in 87 octane and averaged 26mpg in the exact same conditions. People who are using regular gas are saving themselves 5% filling up and giving up 10% of their fuel economy. Premium is cheaper.

NABS4

Your example is annecdotal at best (wind?, elevation?, temperature?, vehicle load?). Truth is there is no difference in fuel economy between regular and premium gas. Your engine had the capability to produce 5 extra hp (or thereabouts) when it was burning higher octane gas. The engine doesn't run "more efficiently" when it's running on premium.

mothership324

I would like to assuage the concerns of those who so pompously questioned my ability to afford premium gas in my new Q5. Please sleep well tonight knowing that I can in fact, afford the gas. The original intent of this post was to determine if there would be adverse effects by not regularly using premium. I do not blindly follow all manufacturer's advice. Read the back of any shampoo bottle. It will tell you to lather twice. So do you? I doubt it. I must say I have enjoyed the spirited posts that really have not come to any consensus. My dealer actually told me that using regular gas now and then won't make a difference. Thanks for everyone's input.

mtberman

Fuel threads are as funny as oil change threads. People who know very little about a topic posting their opinions is a great conversation starter.

Your engine's knock sensor senses when the engine starts acting up (pre-ignition or 'ping') due to low octane fuel. It detects levels of knock you can't hear or feel. To prevent engine damage, the ECU adjusts the engine's running parameters (usually ignition timing) until the ping stops. This may or may not be very noticeable to the driver, depending on the temperature and altitude and a lot of other factors including the driver's experience. Running regular may result in slightly better fuel economy (regular has more energy content than premium) or worse economy, or no change at all. But who wants to "live off the knock sensor" as the guy quoted in Road and Track says?

So, running regular now and then won't hurt anything because they've sort of "idiot-proofed" the whole deal for us. But...

There is one constant result of running regular in a car that's recommended for premium: The engine will produce less power at any given speed. That's not an opinion, it's a fact. Here's just one example, from way back in 2001, of a test that lays this all out in terms even a non-engineer like me can understand. The material may be old, but it's still as accurate now as it was 10+ years ago: http://www.caranddriver.com/features/regular-or-premium

I'm no engineer but I am a car guy. I'll go with my what people who are smarter than me advise, based on their real-world tests.

Lyth

Had a 95 Chevy s10 pickup with the 4.3L TBI Vortec and that truck ran like dog crap on regular. If someone borrowed It and filled up with anything other than super I knew right away.

Had a 89 525i and experienced similar results

Then in my 09 Acadia it ran regular and if I put premium I couldnt tell a difference in power but it definitely got worse gas mileage.

Now in a pile of other cars I've owned I could never tell any significant difference in octane but definitely in brands.

My 3.2 says 91 or better so I do it. I'm a car guy. I actually ran an extremely busy repair shop for some time. I may be a little more particular or OCD with my cars and bikes than the next person.

For the $3 to $5 difference at the pump filling up and let's say 50 times in a year that's $150 to $250 a year! Seriously people. What are we talking about here. Someone with an econobox would only see about $50/yr in savings lmfao.

hmn4858

And if you had done a search, you would have discovered this topic has already been discussed ad nauseum.

NABS4

And will continue to be. These things never die.