You could get an aerodynamic mpg-improving body kit. I would recommend getting to stage 0 first...

 

Some professional opinions on octane.
Do You Really Need Premium? - Edmunds.com

I was watching TV the other day and a guy was on talking about the difference of car companies recommending 91 or better octane. His main comment was about certain car motors being designed for higher compression. When lower grade fuel is used, the knock sensor system has to kick in to compensate for the lower bang and he claims that it stresses the motor in some way. I wish I had recorded it, I would have loved to upload the video to youtube.

Another article that I found informative.
HowStuffWorks "What does octane mean?"

How much octane does my engine really need? — Yahoo! Autos

Big brother's words:
The Low-Down on High Octane Gasoline

 

Gulp!!! I moved into the city and my gas mileage has dropped. Mind you this is not a complaint because I'm spending $50 less per month on gas but my mileage has dropped. I'm now getting about 22 mpg. The big difference is that my trips are usually under 5 miles. Also, it's winter time so the car is colder at start up. So, if you drive short trips, you will have lower gas mileage. The first 2 or 3 miles the car is still cold so I'm getting about 12 mpg, once warm it gets better.

22 MPG is not bad for my driving, others claim about 18 mpg. An older lady that I was talking to a few months ago was complaining about getting 15 mpg in her Tarus. Well, she drove about 20 miles per week and never gets on the freeway. Can't expect much there, heck she fills up once every 2 months.

Oh, I changed my ScanGauge II view to the following real time settings: Volts - TPS (throttle position) / Temp - Load. What I have discovered is that the gauge has trained me to keep the throttle position at or less than 23% while accelerating and the load at or below 18. Also, I try to never boost unless my temp is over 180 degrees.

 

It's funny you guys talking about 87 octane fuel, here in Australia we have three grades 91, 95 and 98 and the handbook recommends 95 octane fuel. Was there any major differences that anyone knows of between countries motorwise?

 

Unfortunately there is no international standard for octane ratings. Check out the the link below. It contains the most complete expanation I could find.
Modern Vespa : Octane Ratings

Here in the USA we have two rating classes, one for the Rocky Mountain states (85-87-91) and the second for the rest of the USA: (87-89-93).

 

as soon as I changed my spark plugs and got a tune up the mpg went down to 15 from 20-21. I heard spark plugs have alot to do with the gas mileage

 

What plugs did you install? I would only do OEM. What are the new plugs gapped at? How many tanks of gas have you run (it may take a tank or two to get the computer to adjust to the new plugs)?

 

some of the thoughts in the thread make me chuckle alittle.

Honestly, we drive VOLVO's. MPG an and volvo just dont go together well.

my 850t wagon is around 3500 pounds. and with turbo makes 190-200hp(acounting for loss over age)

my 06 scion xb is just 2500 pounds and makes a MASSIVE 103hp

Guess which gets better MPG?

Even tho the scion is an actual BOX, it gets double the MPG, and thats even if I drive the scion with a lead foot and the volvo with MPGs in mind.

But if I wanted an econo box MPG lightwieght car I would have bought one. Volvos are awsome cause they are Overbuilt. More steel, heavier and longer lasting engine ect.
And obviously in a crash I would rather be in a volvo than in the scion.
Not trashing my toaster either, I like it. Its a toyota so MPG and reliability are high. But it doesnt have the feel of quality that my 17 year old 850 does.

Really, beyond proper tune-ups there isnt much we can do about MPGs. Its simply a COST of owning a great kind of car.

 

I personally know that I get bad gas mileage because of my right foot....lol I have a 96 turbo and get 23 highway and that is running 75 mph to and from work I also using regular low grade fuel.
I did get bad gas mileage because I had an issue with my front tires it dropped to 18 or MPG
Also I have check engine code for a bad gas cap or air leak? Its not the gas cap, and cannot find any other issues, just have the light on now

 

For the vehicle class, 850s are fuel efficient, apples to apples. Besides 02 sensor which can get weak and should be replaced, EVAP leaks are common. They are not easy to find, yet very inexpensive to fix.

 

Just wanted to let you guys know, especially the big contributors like rspi, mattyxxl, matt01 etc., using the info on this thread I have nearly doubled the fuel mileage on my car since I bought it last September. DIY is saving the planet, the fuel economy repairs I have done have been cheap and I am building way more power than ever before (still probably less than stock).

You guys rule.

 

Not sure what people are smoking but personally I go by the manual from the volvo manufacturer. It is very clear that they do not recommend premium gas for the car and on several pages they remind you to not use premium.

 

What manual do you have?

 

Here is a link to the manual for anyone else that can't find the proper info: http://new.volvocars.com/ownersdocs/..._401.htm#pg4.3

 

So can i trust the reading for mpg that the trip computer is giving me? or do i have to buy one of those readers.

 

You can test the dash by running a tank manually. Fill the tank, reset the mileage in the trip computer (I believe the 3 o'clock position is the trip mileage) and the MPG in the computer (11 o'clock), run the tank down less than 1/2 tank, fill the tank back up, divide the mileage by gallons pumped and you'll have your mileage, then compare it to the dash read out at 11 o'clock and that will tell you how accurate it is.

 

You ought to post the things you did to your ar so others can try the same, maybe we an get some extra horses and economy with your ideas.

 

NOT use PREMIUM !!! You reading that out of your lawn mower manual or what

Maybe you have the "ACME" manual sourced where the road runner went for most of his gadgets but in my manual it states that the minimum is 87. Not the recommended, the minimum is 87. My Volvo owners manual states the engines are designed to run on premium with a minimum of 91 octane for optimum performance. So to me the words minimum and optimum would lead me to make the statement that you can use regular but what you save in per gallon at the pump you're likely throwing away squirting more of it into the engine because it will ping and or knock and retard your timing. That would also take a lot of the fun out of it because with the timing retarded you will not have the acceleration or power that make the engine fun.
You might get away with running regular but it isn't what they recommend. It also can cost you because if the cheaper gas causes the engine to knock the computer will automatically retard timing causing you to use much more fuel for the same amount of power.

 

to kiss 4afrog, rspi, and everyone else in this thread I formally would like to apologize. I am not sure what I was smoking but would have sworn on my life my manual stated not to use premium. After further review I am a complete moron and you guys are 100% correct. Just started using premium myself and can really tell the difference in performance.

 

Being wrong is just another way of finding out what's right.
Been there, done that and positive I'll be there again !